Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number SD4-5A found under Fuse Cartridge by San O Industrial Corp. The National Stock Number assigned to this part is 5920002805066, and the Federal Supply Class is 5920 Fuses Arresters Absorbers And Protector. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like SD4-5A.