Extrema Ratio BFK Knife Black Aluminium, Black N690 (04.1000.0178/BLK/A1)

Extrema Ratio BFK Black Aluminum, Black N690 – Full-Size EDC Folding Knife with Crossbar Lock

The Extrema Ratio BFK 04.1000.0178/BLK/A1 is a full-size folding knife designed for everyday carry and regular use. The Böhler N690 steel blade with a black coating and the black anodized aluminum handle create the compact, technical design characteristic of Extrema Ratio.

This model features a double-sided Crossbar Lock and a hole in the blade for convenient one-handed opening. Milled grips improve grip control, and a reversible clip allows the knife to be carried on the right or left side in a tip-up configuration.

Böhler N690 – Proven Steel for Everyday Use

The blade is made of Böhler N690 steel hardened to 58 HRC. The material offers good corrosion resistance, adequate toughness, and stable edge properties, making it well-suited for a knife intended for regular use.

Flat grind – versatile geometry

The flat grind ensures predictable blade guidance through materials and performs well across a wide range of everyday tasks. With a thickness of 2.75 mm, it maintains good cutting performance without excessively increasing the blade’s weight.

Black-coated blade finish

The Black version features a black-coated blade finish, which emphasizes the model’s understated, functional character. The dark surface complements the black anodized handle and other structural elements well.

Anodized aluminum and milled grips

The handle is made of anodized aluminum. The milled surface improves grip and makes it easier to control the knife with both dry and wet hands, while maintaining a slim profile suitable for everyday carry.

Crossbar Lock – ambidextrous operation

The Crossbar Lock allows you to conveniently release the lock from either side of the handle. The mechanism keeps your fingers out of the path of the closing blade and works well for both right- and left-handed users.

Thumb Hole – One-Handed Opening

The Thumb Hole is used to open the blade. It allows for intuitive one-handed operation of the knife and works well with the ambidextrous nature of the Crossbar Lock.

Reversible clip and aluminum backspacer

The clip is made of stainless steel and is designed to be mounted on either the right or left side of the handle in a tip-up configuration. The black aluminum backspacer completes the handle design and maintains material consistency throughout the entire model.

Why Choose the Extrema Ratio BFK Black?

This is an option for users looking for a full-size EDC folder with a solid construction and ambidextrous operation. The N690 blade, Crossbar Lock, milled aluminum handle, and reversible clip create a practical set for everyday carry and work.

Key Features at a Glance

• Böhler N690 – steel with good corrosion resistance and stable performance characteristics.
• 58 HRC – blade hardness.
• Flat – flat grind.
• Burnished – black-coated blade finish.
• Anodized Aluminum – a lightweight and rigid handle.
• Crossbar Lock – double-sided blade lock.
• Thumb Hole – one-handed opening.
• Right/left clip, tip-up – fully customizable carrying options.

Technical data

Frequently Asked Questions

What are the advantages of Böhler N690 steel?

N690 offers good corrosion resistance, a stable cutting edge, and reasonable ease of maintenance. This makes it well-suited for knives intended for regular, everyday use.

How does the Crossbar Lock work?

The mechanism uses a crossbar to lock the blade in the open position. It can be operated from either side of the handle, making it easy to use with either the right or left hand.

Can the BFK be opened with one hand?

Yes. The thumb hole allows you to comfortably open the blade with your thumb, without needing to use your other hand.

Is the clip reversible?

Yes. It can be mounted on the right or left side of the Handle in a tip-up configuration.

What is the Extrema Ratio BFK best suited for?

This model was designed as a full-size EDC folder for everyday utility tasks. It works well for opening packages, cutting materials, and other typical tasks performed throughout the day.

Prepared by: Specialists at Sharg® company – Your expert in EDC and cutting tools