Extrema Ratio S.R.L. Via Traversa delle Ripalte,72/78 | 59100 Prato (PO) Italy | P.I.02481870976
We subject prototypes and production samples to the most rigorous NATO tests to achieve the development of high-performance products, supplemented by a series of even more rigorous and specific tests developed in-house. We also carry out comparative tests with the most representative models produced by competing companies to ensure absolute effectiveness. Standard tests are aimed at defining product limits based on the following parameters:
For our blades we mainly use BÖHLER N690 steel alloy, a martensitic steel enriched with chromium, vanadium, molybdenum and cobalt with excellent homogeneity and transformed into plates for lamination.
We capitalize on almost ten years of experience in using this steel, we treat it with all the precautions and methods that lead it to reach its highest performance; high-power laser cutting, vacuum heat treatment, special micro-peening, burnishing and carbonitriding protection that meets the most demanding military specifications – treatments that we use for all our production, both military and civil.
This Austrian steel proved to be a magnificent compromise between hardness, elasticity, and stainlessness. Our goal is not the perfect blade, but to offer our professional customers a truly functional and effective blade for large-scale use.
With our blades we have rewritten European military standards.
In addition, our blades are all sharpened manually. This allows us to obtain intrinsic characteristics that differ from industrial sharpening, which result in robust and durable as well as effective sharpening.
We have developed the ERMH (Extrema Ratio Multipurpose Handle) in collaboration with the Faculty of Motor Sciences of the University of Perugia, a handle that lends itself extraordinarily well to work and combat. Its grip is delegated to a socket that thins the handle providing a useful grip to the three strong fingers of the hand, which make up the opposable system.
The asymmetrical but straight handle, which allows the dynamic grip to change from sabre to reverse, ends of the through shank protrude which can be used as a loop or as a blunt protrusion.
It adapts to male and female hands of every size and to thermal gloves.
It is monobloc, meaning that it can be disassembled easily and allows an excellent degree of ordinary and extraordinary maintenance to the knife.
It is produced by injection in Forprene, an elastomer with a resistance to extreme temperatures (-40/+120) that allows it to pass NATO tests. Some models, such as the back-ups, use the same handle but in ERMH C version, which is more compact, more suitable for concealment and with lower risk of entanglement – the bare minimum for a firm grip.
All other handles are produced either in Forprene, loaded with fiberglass in case of need, or in Nylon, when it is necessary to use a stiffer polymer, always compliant with NATO specifications.
We mainly use Anticorodal for the handles, an aluminium alloy with high mechanical characteristics and a considerable resistance to oxidation.
The burnishing of the Anticorodal parts takes place through high thickness anodic oxidation.
The metal components are made of N690 (such as the blade) when high hardness is required; AISI 304 and AISI 303 are used when high resistance to oxidation is required (screws, pins, turning).
The blackening of the steel parts takes place either by carbonitriding (with zirconium) or by burnishing to military specifications (MIL-C-13924). The springs are made of stainless steel.
The ergonomics of the grips follow the same criteria as the fixed blade. In this case, however, the socket on the front of the handle facilitates the engagement of the opening pin, which in any case remains within the shape of the closed knife.
Most folding knives are equipped with a Widia glass-breaker tip or, as in the case of heavy-duty folding knives, have a hardened steel pommel that protrudes from the back of the sheath.
We use various time-tested blade locking systems such as the back lock or the liner lock.
We pay particular attention to the development of sheaths, which represent – as the handles – the interface between the blade and the user, in this specific case between the blade and the user’s standard equipment.
The sheaths of fixed blades and bayonets generally have at least two retention systems, both ambidextrous; one is automatic that works with pressure, the other is manual.
The first is built-in in the rigid part of the sheath, and it is a pressure mechanism that prevents the loss of the blade in the event of overturning or rolling; the second is generally a two-button lace that holds the upper part of the handle of the knife close to the body so to avoid any entanglement with vegetation, other parts of the equipment (such as rifle belts) or worse – in case of a parachute launch, with constraining rope or parachute lanyards. The carry is comfortable and noiseless.
The insertion is made easier by a large safety lever especially when the sheath is hidden by magazine pouches or other accessories. The rigid sheath prevents the blade from escaping even in the event of severe shocks and, since it quickly dries thanks to the lower drainage hole, it prevents the blade from long exposure to agents that favour the oxidation process.
The soft part of the sheath contains the rigid sheath, making it more adaptable to the rest of the equipment with straps or M.O.L.L.E. system webbings. In addition, it wraps it around, reducing the noise emission caused by the possible collisions between the sheath and other rigid elements.
The tapes and accessories are in Nylon or Cordura; all the buttons and metal parts are made of burnished brass or covered with polymer. Semi-rigid sheaths, as in our bayonets, KS and KH, are made of Nylon or Cordura coupled with closed-cell elastomers, which do not absorb water and moisture.
As outlined in the previous paragraphs, we pay the utmost attention to the safety and carry of the knives starting from their design phase.
We analyse possible problems related to the noise during transport, entanglement with the rest of the individual equipment and with natural or artificial obstacles, and behaviour inside vehicles and aircrafts.
We then take into consideration the safety in extraction and insertion of the knife, with particular attention against intentional theft.