5/16 Short Arm Alloy Steel Hex Key is selected when a worn or undersize key should be replaced before it damages the screw socket. The ASME B18.3 width band is 0.3110-0.3125 in.; the key is held just under nominal so it enters an in-tolerance socket and bears on the flats.
Repair benches use short and long formats to cover both open access and recessed socket locations. Use the Short Arm series when clearance is limited, and compare the Long Arm twin when added reach is needed.
Cold Headers supports exact-size sourcing for socket-product tooling, including individual alloy steel L-keys. Review the 5/16 in. width, Short Arm format, short-leg length, and arm length before ordering. The listed B and C ranges keep the tool geometry tied to this exact catalog row. That context helps purchasing compare the driver geometry without adding unsupported performance claims.
Call 773-775-7900 or email Sales@coldheaders.com for pricing, availability, or a quote.
