Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number MX421B-10 found under by Mx Marine Inc. The National Stock Number assigned to this part is 5825015831259, and the Federal Supply Class is 5825 Radio Navigation Equipment Except Airborne. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like MX421B-10.