Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 21571-4-2 found under Synchronizer Module by Bei Sensors And Systems Co Inc. The National Stock Number assigned to this part is 7050001396364, and the Federal Supply Class is 7050 Adp Components. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 21571-4-2.