Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number MI51B1 found under Loudspeaker by Raytheon Company. The National Stock Number assigned to this part is 5965005605804, and the Federal Supply Class is 5965 Headsets Handsets Microphones And Speakers. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like MI51B1.