Extrema Ratio knives
Extrema Ratio makes fixed-blade and folding knives for everyday carry, outdoor work and professional field use. Founded in 1997, the company offers designs ranging from compact carry knives to larger working models, with features and materials that vary by model.
The Satre is a lightweight fixed-blade knife for survival, bushcraft and everyday carry. The full-size BF2 folding knife is designed for field use and comes in drop-point and tanto blade profiles. These models illustrate the brand’s compact fixed-blade and locking-folder formats.
Round Patch 85mm Brown
Baseball Cap, black
Estrema Hammer
Forpene handle, desert
Choosing a format
Extrema Ratio’s range includes fixed-blade knives for outdoor tasks and folding knives for pocket carry or field use. The Satre is a compact, lightweight fixed blade intended for survival, bushcraft and everyday carry. Its full-tang skeletonized construction keeps the handle slim and can be wrapped with paracord. A molded Kydex sheath supports neck carry and other carry positions. The BF2 is a full-size folder aimed at professional field use; its folding design makes it a different choice from a fixed blade carried in a sheath.
Materials and model details
Satre steel depends on the version: options include Böhler N690, Böhler S600 and Nitrogen steel. The N690 version is heat-treated to 58 HRC; the S600 version is treated to 64 HRC and has greater wear resistance, but is more difficult to sharpen and can oxidize. Nitrogen-steel versions are offered in high-visibility colors. Check the exact configuration, as steel and finish are not shared across every Satre. The BF2 uses a flat-ground blade in either drop-point or tanto shape. Its blade is Böhler N690 at 58 HRC, with an anodized aluminum handle; selected versions use M390 steel. A liner lock holds the blade open, and a manually operated secondary safety adds another locking step. Blade shape and steel depend on configuration.
Background and coverage
The company dates its origins to 1997 and describes its work across tactical, outdoor and everyday-carry categories. Both Satre and BF2 product pages identify their models as made in Italy; that origin should not be assumed for every product in the range. Extrema Ratio states that its commercial warranty covers functional defects in workmanship, materials or treatments for the life of the knife. Sheaths have two-year commercial coverage, and the policy excludes normal wear, oxidation from insufficient maintenance and damage from misuse.