Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 139-4870 found under Microphone Element by M And S Electronics Inc. The National Stock Number assigned to this part is 5965001394870, 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 139-4870.