Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 904-02-020-1704 found under Washer Lock by Porter Cable Corp. The National Stock Number assigned to this part is 5310015680172, 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 904-02-020-1704.