Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 4431-1 found under Spacer Ring by Pdi Ground Support Systems Inc. The National Stock Number assigned to this part is 5365012753232, and the Federal Supply Class is 5365 Bushings Rings Shims And Spacers. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 4431-1.