Socket Drive Adaptors and Bit Couplers: The Complete List

An adaptor joins a drive of one size to a tool of another, and the only two facts that matter are what it accepts and what it drives. This is the complete list of 36, with both stated for every part.

Stepping down is safe, stepping up is not

A reducing adaptor puts a small socket on a big ratchet. The ratchet can deliver far more torque than the small socket was designed to take, and the socket has no way to warn you — it simply splits. A step-up adaptor does the reverse and is the safer direction, because the limiting component is then the ratchet you are holding, which will feel wrong before anything breaks. Where a step-down is unavoidable, treat the SMALLEST component in the stack as the torque limit for the whole assembly.

Bit couplers are a different thing

A bit coupler converts a square drive into a hex socket that accepts screwdriver or impact bits, so a ratchet can drive a bit. That is genuinely useful — a ratchet gives far more control than a screwdriver on a seized screw — but the hex bit becomes the weak point, and bits are brittle. A bit intended for hand use will shatter rather than bend when a ratchet twists it past its limit, so an impact-rated bit is the right choice anywhere the coupler is on a powered or impact tool.

All 36 adaptors and couplers

Where this list comes from

Every row is read from the live Teng Tools USA catalogue on the day this page was generated — product record, part number and size taken from the record itself, never transcribed from a printed catalogue or inferred from a pattern. The accepts and drives columns are read from the product record for each part; anything whose drive pair could not be read from the record is left out rather than guessed, because an adaptor listed with the wrong pair is a tool that will not fit. A size that has been discontinued disappears from this list rather than lingering as a part number you cannot order, which is the failure mode of every static spec sheet.

Impact adaptors are not optional

Adaptors marked as impact are made from a different steel, heat-treated to a lower hardness so they deform rather than fracture under repeated hammer blows. A chrome adaptor in an impact stack is the most likely component to fail, and it fails by shattering — the square snaps and the socket leaves at speed. It is also the least visible risk in the assembly, because a chrome and an impact adaptor look broadly similar once they are covered in oil.

Adaptors are in sockets and accessories; impact-rated parts are in impact sockets.