This is a 300 mm socket extension bar with a 3/8 inch (9.5 mm) square drive, designed to extend the reach of hand ratchets and socket handles to access fasteners in deep or obstructed locations. Its primary use is to transfer torque from a 3/8" ratchet to a socket where direct access is restricted, allowing technicians to work around obstructions and reach recessed nuts and bolts without dismantling surrounding components.

The extension bar is manufactured from chrome vanadium steel (Cr‑V) and is heat treated to give the torsional strength and wear resistance required for routine workshop and site use. The bar is finished with a polished chrome plating to help resist corrosion and to make cleaning oil and grease simple. Both ends are precision machined to provide accurate square drive engagement; the female end includes a spring‑loaded detent ball for positive socket retention and to prevent accidental disconnection during use.

This 3/8" drive extension conforms to the common requirements for square drive accessories used in conjunction with ISO, DIN and BS standards for hand tool accessories and sockets, and is intended for hand‑tool use. It is not an impact extension and should not be used with pneumatic or impact drivers unless explicitly specified for impact service.

Typical applications include automotive maintenance and repair, plant and machinery maintenance, assembly lines, HVAC installation, marine and rail maintenance, and general mechanical and electrical service work where space is constrained. The 300 mm length is particularly useful for reaching fasteners behind engine components, inside control panels, or in other confined spaces where a ratchet cannot directly reach.

Key benefits include good corrosion resistance from the chrome finish, reliable socket retention via the detent ball, and robust strength from the chrome vanadium construction suitable for standard hand torque. The 3/8" drive provides a good balance between torque capacity and access for medium‑duty fastening tasks and is compatible with the wide range of 3/8" sockets, ratchets and accessories on the market.

Duchy Fasteners stocks this extension bar in a range of lengths and pack quantities; please refer to product code DR13205 for availability and bulk pack options.