Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 999-4567-121A found under Insert Screw Thread by Mpc Products Corporation. The National Stock Number assigned to this part is 5325012181274, and the Federal Supply Class is 5325 Fastening Devices. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 999-4567-121A.