Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 21253 found under Ion Trap Cathode Ra by Canberra Industries Inc. The National Stock Number assigned to this part is 5960012640996, 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 21253.