5-40 x 1 1/4 Alloy Steel Socket Head Cap Screw with Nylon Insert is used where alloy steel socket cap screw fastening needs additional resistance to loosening in service. It is a practical option when purchasing teams want a socket-drive fastener with an integrated nylon insert feature. The nylon insert provides prevailing-torque resistance that can help reduce loosening in machinery subject to vibration or repeated movement. Cold Headers also identifies this nylon insert socket head cap screw family with the 1960 Series. The 5-40 x 1 1/4 size supports exact catalog selection for robotics, packaging machinery, inspection fixtures, and serviceable machine components. 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. Automation systems, tooling plates, machine frames, and engineered fastening locations 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.