Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number R-550 found under Semiconductor Device Diode by Russtech Engineering Co Inc. The National Stock Number assigned to this part is 5961015606728, and the Federal Supply Class is 5961 Semiconductor Devices And Associated Hardware. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like R-550.