Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 651809-020 found under Retainer Electron Tube by Bae Systems Information And Electronic Systems Integration Inc Div Bae Systems. The National Stock Number assigned to this part is 5960002494973, 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 651809-020.