Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number B31-10090-5 found under Washer Key by General Dynamics C4 Systems Inc. The National Stock Number assigned to this part is 5310001861029, 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 B31-10090-5.