Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 21M100P39M found under Electron Tube by Thomas Electronics Inc. The National Stock Number assigned to this part is 5960010598535, and the Federal Supply Class is 5960 Electron Tubes And Associated Hardware. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 21M100P39M.