Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 31S500-2000 found under Pin Spring by Unbrako A Division Of S P S Technolo. The National Stock Number assigned to this part is 5315007023529, and the Federal Supply Class is 5315 Nails Machine Keys And Pins. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 31S500-2000.