Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 5 16 18X1 1 2INSTEELSCREWCAPHEX found under Screw Cap Hexagon H by Elco Industries Inc. The National Stock Number assigned to this part is 5305007610472, and the Federal Supply Class is 5305 Screws. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 5 16 18X1 1 2INSTEELSCREWCAPHEX.