Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 139021 found under Washer Shouldered And Recessed by Tek Precision Co Ltd. The National Stock Number assigned to this part is 5310004387162, 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 139021.