Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number HEX NUT 4 40UNDERSIZE3 16 found under Nut Plain Hexagon by M C L Inc. The National Stock Number assigned to this part is 5310015077478, and the Federal Supply Class is 5310 Nuts And Washers. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like HEX NUT 4 40UNDERSIZE3 16.