Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 631-4-045 found under Ball Mandrel Aircra by Pines Manufacturing Inc. The National Stock Number assigned to this part is 1680015643653, and the Federal Supply Class is 1680 Miscellaneous Aircraft Accessories And Components. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 631-4-045.