Extrema Ratio

Extrema Ratio is an Italian brand of tactical knives, founded in 1997. The company develops knives for military, police, rescue services, and outdoor use. Extrema Ratio officially supplies knives to the Italian armed forces and security forces, and is ISO 9001 certified and has a NATO supplier code.

You can buy original Extrema Ratio knives at MyGoodKnife—our store is the brand's official dealer. Our selection includes folding tactical knives and fixed-blade knives from popular Extrema Ratio series: Col Moschin, Fulcrum, RAO, Caimano Nero, Dobermann, Selvans, Misericordia, S-THIL, and others.

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Folding karambit knife Extrema Ratio Nightmare Stonewashed 04.1000.0454/SW 7.3cm
Folding knife Extrema Ratio Nightmare Stonewashed 7.3cm 04.1000.0454/SW
Extrema Ratio Nightmare is a karambit folding knife with rescue characteristics. It has been adopted by the special units of U.S.I.V.P. Principality of Monaco Police. Its name comes from the development and consultancy department of Monaco special intervention units. It comes with a standard industrial-grade cutter blade which is easily replaced, a reversable pocket clip, a glass braker placed in the finger ring. It is produced both in black and stone washed version.
€241.94

In stock

Folding knife Extrema Ratio Glauca B1 04.1000.0139/BLK 10.7cm
Folding knife Extrema Ratio Glauca B1 10.7cm 04.1000.0139/BLK
This new folding knife comes out from a cooperation and planning phase with G.I.G.N. (special unit of the French national Gendarmerie). To maximize penetration, a special blade tip has been developed. On the back side of the handle it has a special tool to cut plastic handcuffs. It comes with a rear glass breaker, reversible clip and safety lock. The sheath has a hard ABS structure on a cordura basis and it has several possible ways of fixing: MOLLE system for tactical jackets, belt fixing and side fixing. The sheath is planned to be used with open blade knife.
€459.68

Shipping after 10-20 business days

Neck knife Extrema Ratio N.K.1 Black 04.1000.0123/BLK 5.1cm
Fixed blade Knife Extrema Ratio N.K.1 Black 5.1cm 04.1000.0123/BLK
Extrema Ratio N.K.1 Black fixed is a reduced-size knife is based on the skinner and perfected to a true tactical knife. The design of the handle prevents accidental injury while drawing. A groove on the back of the blade accommodates for the user’s index finger or thumb, according to wielding style. Due to its overall construction, the N.K.1 is both capable of offense, through very effective slashing strikes, and useful for minute precision work. Total length 129 mm. Blade length 51 mm. Weight 56 g. The included, rapid- release Kydex sheath comes with a paracord strip for neck carry. Further, it can be attached via MOLLE system to tactical vests or to any of the compatible cordura sheaths from Extrema Ratio. Available but not included: belt clip (for attaching sheath to a belt), polymer under shirt system (for concealed carry). Available versions: N.K.1 Black, N.K.1 Desert Warfare, N.K.1 Stone washed.
€128.23

In stock

Survival knife Extrema Ratio Ontos Black No Kit 0410000127BLKNK 16.8cm
Survival knife Extrema Ratio Ontos Black No Kit 16.8cm 0410000127BLKNK
The Extrema Ratio Ontos Black No Kit is a durable knife for tough outdoor tasks. This version does not include a survival kit. The name ONTOS translates from Greek as "phenomenon." Part of the blade's upper surface is serrated. The 168 mm blade is crafted from premium Bohler N690 steel with a special black MIL-C-13924 coating. The durable black Forprene elastomer handle features a lanyard hole. A M.O.L.L.E. system sheath is included. The knife weighs approximately 411 g.
€319.35

In stock

Folding knife Extrema Ratio BF2 CD Black Ruvido 04.1000.0145/RBV 8.7cm
Folding knife Extrema Ratio BF2 CD Black Ruvido 8.7cm 04.1000.0145/RBV
Extrema Ratio BF2 CD Black Ruvido version. BF2's are “Full size” folding knives especially suitable for professional use by military or police operatives on the field. The handle is solid and comfortable, with the reversible clip becoming a useful and comfortable resting point for the thumb in a “reverse” grip. Characteristical lowered flat areas in the handle give access to the opening “pins”, which don’t protrude from the knife when closed. The flat-ground blade is available in a drop-point or a tanto shape, featuring an extra-thick and stout tip (as in model BF1). The renowned LINER-LOCK blade-blocking system is paired with a carter-protected, manually-activated secondary blocking system.
€181.45

Shipping after 10-20 business days

Tactical knife Extrema Ratio Giant Mamba Black 04.1000.0218/BLK 16.3cm
Fixed blade Knife Extrema Ratio Giant Mamba Black 16.3cm 04.1000.0218/BLK
The Giant Mamba has a 6.3 mm thick, 58 HRC Böhler N690 steel, plain edged tanto blade with full length fuller for lightness finished in black or stone washed. The Forprene grip is affixed by a threaded tang that makes the knife sturdy and well balanced. The injection molded, impact grade nylon, M.O.L.L.E. compatible scabbard has a dampening system to avoid blade rattle, twin button safety loop, anti-rotation rubberized thigh strap and a retention safety disengaged by simple pressure on the trigger-like lever. The new knife line minimizes thickness and bulk without skimping on toughness and safety.
€250.81

Shipping after 10-20 business days

Tactical knife Extrema Ratio Contact Black
Fixed blade Knife Extrema Ratio Contact Black 16.2cm 04.1000.0215/BLK
Contact is a first knife of Extrema Ratio new production line. It has a blade with a lance-shaped profile, a flat grinding and a diamond-shaped geometry. Contact has got a lower guard branch to protect the hand from accidental cuts, upper jumping to improve grip, a concave fuller along the entire length of the blade and a generous thickness blade (6.30mm) All these details make the Contact the elder brother of the now famous Requiem, revisited in proportions and in some technical features. The blade is made in Böhler N690 steel with a hardness of 58 HRC and a chemical burnishing coating for the Black version. The sheath is minimalist; most of the fabric has been cut off; it has got a 2nd level retention system, remembering the style of the model it was inspired by.
€250.81

Shipping after 10-20 business days

Training knife Extrema Ratio TK BF2 04.1000.0145-TK 8.9cm
Training knife Extrema Ratio TK BF2 8.9cm 04.1000.0145-TK
Training knife Extrema Ratio BF2. Extrema Ratio restyled series of training knives are manufactured in a wide range of models of diverse size and shape. They enable martial arts practitioners and professionals to train different combat techniques with an appropriate and dedicated tool. All training knives are produced in a metallic blue colour which makes them easily identified even when sheathed. The blades are produced from anodized aluminum and have the very same shape and size of the Extrema Ratio standard production models. The handles are the same used in our production models. The sheaths, sold separately, are the same used for the real knives. The stiff blade allows for training complex defensive and disarming techniques. We recommend the use of appropriate protective gear when training.
€32.26

In stock

Survival knife Extrema Ratio Ontos Green No Kit 04.1000.0127/GRN-NK 15.9cm - 1
-6%
Survival knife Extrema Ratio Ontos Green No Kit 15.9cm 04.1000.0127/GRN-NK
Growing demand from the professionals amongst our clients persuaded Extrema Ratio to design a survival tool for all seasons. ONTOS (“the thing” in Greek) is a pure field knife, tough and heavyweight despite its compact size. The serrated segment on the back of the blade is meant as a back-up, never to be caught without a sharp edge ready for use. The MOLLE compatible nylon thigh sheath stays on even in the event of a retreat, when a soldier would drop most of his cumbersome primary equipment. It is possible to buy separately a survival kit to be fixed to knife sheath. Available versions: ONTOS BLACK, ONTOS GREEN.
€300.19
€319.35

In stock

Multi-tool Extrema Ratio TK Tool 2.0 Stonewashed tksw 10cm - 1
Multi-tool Extrema Ratio TK Tool 2.0 Stonewashed 10cm 04.1000.0050/SW
Extrema Ratio multifunctional tool with a basic and essential design, jointly developed with military professionals. It features a special tip useful for adjusting and calibrating firearm optics. The front of a TK TOOL 2.0 can be used as a screwdriver suitable for 8/10 mm screws, or as a prying lever. The central slot in the blade can be used as a shackle key. This tool has also features two holes for a cord or paracord used in assembling a field or camping tent. Overall, a much sought-after tool for a number of outdoor activities. MOLLE system compliant.
€63.71

Shipping after 10-20 business days

Tactical knife Extrema Ratio Operativo 39-09 Operativo
Fixed blade Knife Extrema Ratio 39-09 Operativo 19.5cm 04.1000.0339/BLK-OP
Extrema Ration 39-09 Operativo is the result of a project sponsored by COFS (the inter-force operations command for Italian special forces) and its former Commander-in-chief, Gen. Bertolini. This combat knife 39-09 is a restyling of the Model 1939 “paracadutista assaltatore” (assault paratrooper) knife, a celebrated piece of Italian military history.
Small changes which make it a highly effective, dependable dagger. The included hard sheath is designed to be worn at the ankle, in the characteristic fashion of Italian paratroopers.
The 39-09 Operativo version has Forprene handle, black blade oxide-coated, no logo. It comes in a black belt sheath. Weight  338 g (11.9 oz)
€350.00

In stock

Training knife Extrema Ratio TK Suppressor 04.1000.0312-TK 17.6cm - 1
Training knife Extrema Ratio TK Suppressor 17.6cm 04.1000.0312-TK
Suppressor training knife. Extrema Ratio restyled series of training knives are manufactured in a wide range of models of diverse size and shape. They enable martial arts practitioners and professionals to train different combat techniques with an appropriate and dedicated tool. All training knives are produced in a metallic blue colour which makes them easily identified even when sheathed. The blades are produced from anodized aluminum and have the very same shape and size of the Extrema Ratio standard production models. The handles are the same used in our production models. The sheaths, sold separately, are the same used for the real knives. The stiff blade allows for training complex defensive and disarming techniques. We recommend the use of appropriate protective gear when training.
€51.61

In stock

Folding knife Extrema Ratio BF0 R CD Desert 04.1000.0461/DW 5.5cm - 1
Folding knife Extrema Ratio BF0 R CD Desert 5.5cm 04.1000.0461/DW
BF0 R CD folding knife with Desert handle. Extrema Ratio is proud to present the new basic folder BF0 R CD. It is a small Basic folders. Its handle produced in technopolymer makes it light and resistant, also thanks to its steel internal frame. BF0 R CD employs the trustworthy LINER-LOCK blade blocking system. It keeps all BF0 characteristics improved with new High Speed Razor Opening System. Available versions: Black, Desert, HCS, Ranger Green, Wolf Grey
€65.32

In stock

Folding knife Extrema Ratio BF0 R CD Ranger Green 04.1000.0461/GRN 5.5cm - 1
Folding knife Extrema Ratio BF0 R CD Ranger Green 5.5cm 04.1000.0461/GRN
BF0 R CD folding knife with Tanger Green handle. HCS Extrema Ratio is proud to present the new basic folder BF0 R CD. It is a small Basic folders. Its handle produced in technopolymer makes it light and resistant, also thanks to its steel internal frame. BF0 R CD employs the trustworthy LINER-LOCK blade blocking system. It keeps all BF0 characteristics improved with new High Speed Razor Opening System. Available versions: Black, Desert, HCS, Ranger Green, Wolf Grey
€67.73

In stock

Folding knife Extrema Ratio BF0 R CD HCS 04.1000.0461/HSC 5.5cm - 1
Folding knife Extrema Ratio BF0 R CD HCS 5.5cm 0410000461HSC
BF0 R CD folding knife with HCS handle. HCS Extrema Ratio is proud to present the new basic folder BF0 R CD. It is a small Basic folders. Its handle produced in technopolymer makes it light and resistant, also thanks to its steel internal frame. BF0 R CD employs the trustworthy LINER-LOCK blade blocking system. It keeps all BF0 characteristics improved with new High Speed Razor Opening System. Available versions: Black, Desert, HCS, Ranger Green, Wolf Grey
€65.32

In stock

Folding knife Extrema Ratio BF0 R CD Black 04.1000.0461/SW 5.5cm - 1
Folding knife Extrema Ratio BF0 R CD Black 5.5cm 04.1000.0461/SW
Extrema Ratio is proud to present the new basic folder BF0 R CD. It is a small Basic folders. Its handle produced in technopolymer makes it light and resistant, also thanks to its steel internal frame. BF0 R CD employs the trustworthy LINER-LOCK blade blocking system. It keeps all BF0 characteristics improved with new High Speed Razor Opening System. Available versions: Black, Desert, HCS, Ranger Green, Wolf Grey
€65.32

In stock

Sharpening stone Extrema Ratio Double grain 0441000102 - 1
Sharpening stone Extrema Ratio Double grain
Extrema Ratio Double grain sharpener in silicon carbide. It is composed of a rough grain side (180) and a fine grain side (400) to carry out a more performing sharpening. Extrema Ratio Double grain sharpener comes with a cordura sheath
€38.70

In stock

Hunting and Outdoor knife Extrema Ratio Dobermann IV S Africa erd4af 14.3cm - 1
Fixed blade Knife Extrema Ratio Dobermann IV Africa 18.5cm 04.1000.0184/AFR
Dobermann IV S Africa, a knife dedicated to hunters, projected to skin and work on the prey. It comes with a 185 mm satin blade. Dobermann IV S Africa will come with two different handles: one in santos rosewood and one in forprene. In this way the user can easily change the handle, depending on his needs. Moreover it will come with an Italian handmade leather sheath, a sharpener and a stainless steel marlin spike. There are only best hunting knives in MyGoodKnife's range.
€540.32

Shipping after 10-20 business days

Folding knife Extrema Ratio BF1 CD Black Ruvido 04.1000.0143/RVB 6.9cm - 1
Folding knife Extrema Ratio BF1 CD Black Ruvido 6.9cm 04.1000.0143/RVB
BF1 is a folding knife for everyday use: simple, essential and functional. The blade is burnished, with a flat grind and a thick, durable tip. Characteristical lowered flat areas in the handle – also burnished black give access to the opening “pins”, which don’t protrude from the knife when closed. The reversible clip is located on the back of the blade and engulfs its tang – making it discreet to carry. Employs the trustworthy LINER-LOCK blade blocking system.
€153.23

In stock

Folding knife Extrema Ratio BF3 Dark Talon
Folding knife Extrema Ratio BF3 Dark Talon 12cm 04.1000.0158/BLK
The common features of the "Basic Folder" series, including the BF1 and BF2, are lightness, simplicity and ease of carry. BF1 e BF2 are utility knives, the BF3 is both a utility and a combat knife. The blade is sharp and piercing, the carry (where legally allowed) is sufficiently comfortable. The “bridge like” clip and a long enough pocket will properly conceal the knife. Slim and essential.
€183.87

In stock

Tactical knife Extrema Ratio Fulcrum Black 04.1000.0082/BLK 17.1cm - 1
Fixed blade Knife Extrema Ratio Fulcrum FH Black 17.1cm 04.1000.0082/BLK
Probably a milestone among multipurpose knives. Employed on a large scale in Afghanistan as standard equipment by the members of the Italian mission "Nibbio", it is part of an experimental project undertaken by the Alpine Troops Headquarters on the renewal of individual equipment. During the preparation for this mission, the Alpine Troops Headquarters coordinated a team of companies in the realization of a new and complete experimental kit of individual equipment. Extrema Ratio is the company that the Alpine Troops Headquarters chose for the development of a multipurpose knife suitable for the infantry, a knife that could be used in any action and that could successfully solve any type of problem even where more specialized equipment proved inadequate.It was so successful that the multipurpose knife then led to the development of the Fulcrum Bayonet, which had the same characteristics but could be fixed to the issued rifle. The Fulcrum is an extremely robust and versatile knife, the blade can take loads over 150kg without breaking, the point is incredibly robust and the "tanto" profile means the knife can be used for long periods without affecting the sharpness of the last section, this guarantees, together with the partially sharp dorsal blade, (the civilian version does not include this), its capacity for penetration which is necessary in close combat against targets with heavy clothing, garnments and soft ballistic protection. The forward centre of gravity and the weight of the blade make it suitable for heavy field work. The new automatic hard sheath means it can be carried both safely and comfortably and the lace that holds the upper part of the handle dramatically reduces the risk of entanglement, even when making parachute jumps. The speed and facility with which both ordinary and extraordinary maintenance can be carried out help to make Fulcrum an excellent choice for use on a large scale from an economic and administrative point of view.
€295.16

Shipping after 10-20 business days

Diving knife Extrema Ratio BF2 V 04.1000.0147/SW 6.5cm - 1
Diving knife Extrema Ratio BF2 V 6.5cm 04.1000.0147/SW
Boatswain's knife. Thanks to extremely compact shape typical of BF Extrema Ratio models, the extraction of the knife from the pocket becomes easier and it prevents the tool from entangling, a crucial detail in case of emergency. The blade has a flat grinding which allows symmetrical cutting jobs symmetrical with wider support. On the other hand the tip which is thick and durable thanks to the “tanto” version, allows a greater penetration and a more clean and precise cut.The aluminum handle, has the typical "Tactical" structure, already used in the past on the BF models.It has got a pattern of concentric circles giving the handle an additional grip. This structure enables the rinsing of the handle from salt, or organic material, very important considering its primary use in the naval environment. In the central part of the handle its placed a small slot to allow to lock or unlock small wrenches. In the right part of the handle, in correspondence of the liner lock, a steel plate is placed to give a more solid structure to the slot. The BF2 V comes with just one stone washed finishing to find it easier. The same finishing is proposed for the accessories: •reversible clip applicable on both right or left side of handle. •screw regulation system with 12 positions to control the closing and opening of the blade. •marlin sparkle on the tang of the handle with a length of 70mm to untie knots in ropes or thick cords. In opened position it is fixed by a steel mechanism easy to activate and placed inside the handle in order to feel it while handling the knife. It comes with a plastic lanyard with a fix to be fix to the belt, with a joint to allow the different placements and with a quick release simply pushing of the clip button. The length and flexibility of the lanyard allows to work with the tool in the maximum operating area what a shorter lanyard would not allow
€209.68

In stock

Extrema Ratio knives are part of the equipment of many special military units in Italy, as well as police and rescue services. Each model is developed very carefully and undergoes a series of strict tests before being launched into production. The company collaborates with the University of Perugia, where scientists conduct a number of studies, determining the ergonomics of Extrema Ratio products and methods for their improvement. Both Extrema Ratio tactical knives and utility knives are distinguished by impeccable quality. Most knives are made from Austrian N690 steel. Extrema Ratio uses Böhler N690 due to its reliability and predictability. This steel is known for its increased content of molybdenum and cobalt and is characterized by high corrosion resistance. Thanks to this, N690 steel has increased strength and resists impact loads well, which is especially important for tactical use.

Popular Extrema Ratio knife models

The most popular Extrema Ratio knives are Fulcrum, Col Moschin, RAO, Adra. Extrema Ratio also produces several lines of tactical folding knives: BF (basic folder), MF (medium folder), BD4 and BD2 series. Folding models can also be used in urban conditions.

Frequently asked questions about Extrema Ratio knives

What does Extrema Ratio mean?

Extrema Ratio translated from Latin means “extreme measures”. The name reflects the philosophy of the brand: knives are created for situations where maximum reliability, control and readiness for extreme conditions are important.

Where are Extrema Ratio knives made?

Extrema Ratio knives are fully manufactured in Italy. The company is based in the city of Prato and controls the entire process — from development to assembly. The brand is an official supplier for military and law enforcement structures and has NATO supplier certification.

Which Extrema Ratio knife is used by the military?

One of the most well-known models is Col Moschin, developed for the 9th Parachute Assault Regiment of the Italian special forces. Models Fulcrum, Requiem and other knives created for specific unit tasks are also used.

Is it worth buying Extrema Ratio knives?

If you need an extremely strong and reliable knife for tactical tasks, outdoor or intensive use — yes. Extrema Ratio is a tool with a strength reserve, designed for real load. Extrema Ratio knives are also distinguished by the highest assembly quality. Over many years of our store’s operation, this brand has the lowest number of customer complaints regarding product quality.

In the MyGoodKnife online store you can buy original Extrema Ratio knives — we are an official dealer of the brand and offer only authentic products with worldwide shipping.