13Pcs Inch Extra Long Hex Key Wrench

That is the whole point of this page. Consider 1/4 inch: it is 6.35mm. A 6mm metric key will go into a 1/4" socket head, it will feel like it fits, and it has a third of a millimetre of slop — which under load bears on the corners of the recess and rounds it. Five-sixteenths is 7.94mm against an 8mm key; three-eighths is 9.53mm against 10mm. In every case the metric key is either slightly small and will round the socket, or slightly large and will not enter while feeling as though it nearly does.

Imported machinery, American and older British equipment, air conditioning plant, generators, compressors, motorcycles and a good deal of imported hardware all use inch hex fasteners. A workshop with only metric keys will meet them, force a near-fit, and round a socket head that had nothing wrong with it.

The set covers thirteen sizes: 1/20", 1/16", 5/64", 3/32", 7/64", 1/8", 9/64", 5/32", 3/16", 7/32", 1/4", 5/16" and 3/8" — a genuinely complete spread from very fine instrument work up to substantial machinery fixings.

These are extra long, giving the reach into deep counterbores that recessed socket heads so often sit in, and they are fully hardened chrome vanadium steel rather than the S2 used on the metric sets. Chrome vanadium gives hardness and wear resistance from the chromium and toughness from the vanadium.

The buyers are HVAC and refrigeration engineers, generator and compressor servicing, machinery importers and installers, motorcycle specialists working on American and British machines, industrial maintenance, and hardware dealers supplying the plant trades.

If a hex key feels loose in a recess, stop and check whether you are mixing systems — that feeling is the warning, and carrying on is what rounds the fastener. Ask us on WhatsApp for a price.