The Extrema Ratio AERO FX Nitrogen Black Blue fixed-blade knife features a much more understated colour scheme than some other versions in the range; its black handle retains the Italian brand’s instantly recognisable identity, whilst the electric blue detail provides just the right amount of contrast to highlight the particularly minimalist design of this small EDC fixed-blade knife.

The AERO FX features a skeletonised full-tang construction, extensively hollowed out to remove all superfluous material. This allows Extrema Ratio to achieve an extremely slim and lightweight profile without compromising the rigidity expected of a true fixed-blade knife.

The blade is made from Nitrogen steel and features a MIL-C-13924 burnished finish. Its flat grind prioritises cutting performance, whilst its construction deliberately retains the robustness characteristic of Extrema Ratio products.

The handle is made from Anticorodal aluminium. Its blue coloured element is interchangeable: Extrema Ratio has designed the various components of the AERO FX to allow the colour combination to be easily changed.

Particular attention has also been paid to portability. The main Kydex sheath features an ultra-slim profile, complemented by a second Kydex attachment point to expand mounting options. Paracord and double cut-resistant rubber loops for horizontal carry are also included.

Technical specifications of the Extrema Ratio AERO FX Nitrogen Black Blue fixed-blade knife:
Brand: Extrema Ratio
Model: AERO FX
Version: Nitrogen Black Blue
Manufactured in: Italy
Type: EDC fixed-blade knife
Construction: skeletonised full tang
Total knife length: 19.1 cm
Blade length: 8.0 cm
Handle length: 11.1 cm
Blade thickness: 4.8 mm
Steel: Nitrogen
Blade finish: MIL-C-13924 burnishing
Grind: flat
Handle: Anticorodal aluminium
Handle colour: black
Detail: blue
Handle components: interchangeable
Claimed weight: 92 g
Sheath: ultra-thin Kydex
Accessories included: additional Kydex insert, paracord and double loops for horizontal carry

Tellknives review:
Of the various versions of the AERO FX available, the Black Blue is probably one of the most accessible; the black base remains true to Extrema Ratio’s traditional aesthetic, but the electric blue detail is enough to set the knife apart from purely tactical designs.
It’s a more subtle contrast than the Black Lime or the Blue Orange and, in our view, particularly well-suited to an EDC.

The appeal of the AERO FX, however, goes far beyond its colours. Its skeletonised construction shows that Extrema Ratio has genuinely sought to rethink the fixed-blade knife with everyday carry in mind: less material, less thickness and a particularly flat Kydex system.

The brand nevertheless retains some of its core features: full-tang construction, Nitrogen steel and a design that clearly prioritises strength over the pursuit of minimal weight at all costs.

Finally, we appreciate the concept of interchangeable handle components. It transforms colour into a genuine component of the knife rather than merely an aesthetic variation.

The Black Blue will probably be our choice for anyone wishing to discover the AERO FX without opting for the collection’s more eye-catching or outdoor-style colour combinations.