18-8 USS Stainless Nylon Insert Lock Nuts 1/2-20 Qty: 50 (Nylock). Threads are molded into the nylon insert locking the bolt into place. Nylon Insert Lock Nuts typically have a cased metal outside formed into a hex pattern easily torqued by a wrench or socket. Type NE 18-8 Stainless Steel material. ASME B1.1 UNC and UNF Class 2B thread requirement. Stainless Steel material.