Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 521 0048 found under Semiconductor Devic by Kepco Inc. The National Stock Number assigned to this part is 5961011312111, 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 521 0048.