4-40 x 1 1/4 Alloy Steel Socket Head Cap Screw with Nylon Insert is selected where socket head cap screw strength and nylon insert locking support are needed in one fastener. This feature is useful for OEM equipment, automation systems, covers, guards, and service locations where joint retention matters. Alloy steel construction and internal hex drive access support machine-building applications that still require practical installation. Cold Headers also identifies this nylon insert socket head cap screw family with the 1960 Series. The 4-40 x 1 1/4 size supports exact catalog selection for OEM production, distributor stock programs, plant maintenance, and repair departments. For engineers, OEM manufacturers, purchasing managers, and maintenance professionals, this alloy steel part helps match the fastener to the assembly without changing the locked dimensions. Machine building, tooling, fixtures, automation equipment, and oem machinery are common sourcing contexts for this product family. Call Cold Headers at 773-775-7900 or email Sales@coldheaders.com for pricing, availability, or a quote.