Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number C1221 21 4 found under Guard Switch by A P M Hexseal Corporation. The National Stock Number assigned to this part is 5930016080686, and the Federal Supply Class is 5930 Switches. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like C1221 21 4.