This is an 8-piece AF (across flats) hexagon key set supplied on a retaining ring, designed for turning internal hex (Allen) fasteners in metric applications. The set provides a range of compact L-shaped keys with short arms for high torque and long arms for reach, making it suitable for assembly, maintenance and adjustment tasks where space and control are both important.

The keys are manufactured from chrome vanadium (Cr-V) steel and are heat-treated to increase torsional strength and wear resistance. Each key is finished in a black oxide coating to give basic corrosion protection and to reduce surface glare. The set conforms to industry dimensional tolerances for hexagon keys (manufactured to recognised DIN/ISO/BS standards for hex keys), and is intended for use with standard internal hex fasteners such as ISO 4762 hexagon socket head cap screws and similar metric socket screws. Thread type is not applicable for the tool itself; the drive is internal hex via the key’s hexagonal section and the head form is the conventional L‑shape with defined across‑flats dimensions.

Typical applications include mechanical and plant maintenance, automotive and motorcycle workshops, cycle repair, furniture assembly and general engineering work where metric socket screws are common. The compact set on a ring is particularly useful for service engineers and site technicians who need an organised, portable selection of sizes that will not be easily lost. The design allows quick selection and return to the ring while keeping the keys together in a toolbox or on the job.

Key benefits are the material choice and heat treatment for reliable torsional strength, the black oxide finish for moderate corrosion resistance in everyday environments, and broad compatibility with ISO metric hex socket fasteners. Duchy Fasteners stocks this 8-piece metric set in the common range (typically 1.5 mm to 8 mm) supplied on a ring, and can also supply individual replacement keys and larger sets to suit workshop requirements.