Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number S550A found under Rectifier Metallic by St Semicon Inc. The National Stock Number assigned to this part is 6130004072954, and the Federal Supply Class is 6130 Converters Electrical Non Rotating. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like S550A.