Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 4-21-3012 found under Pin by Sargent Welch Scientific Co. The National Stock Number assigned to this part is 5315010643740, 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 4-21-3012.