3/8 Long Arm Alloy Steel Hex Key is a row-specific alloy steel hex key for buyers matching tool crib stock to socket-product drawings. The ASME B18.3 width band is 0.3735-0.3750 in.; the key is held just under nominal so it enters an in-tolerance socket and bears on the flats.
Production cells often keep common widths at the fixture so operators do not borrow the wrong driver. Long Arm geometry adds reach and leverage; the same width in Short Arm form is the natural compact comparison.
Since 1962, Cold Headers has supplied specialty socket hardware and the hex keys that complete the working system. Review the 3/8 in. width, Long Arm format, short-leg length, and arm length before ordering. Cold Headers can review non-catalog widths or arm-series requirements as quote requests. The listed B and C ranges keep the tool geometry tied to this exact catalog row.
Call 773-775-7900 or email Sales@coldheaders.com for pricing, availability, or a quote.
