Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number B391-1 found under Rectifier Semiconductor Device by Therm Air Mfg Co Inc. The National Stock Number assigned to this part is 5961002326649, 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 B391-1.