Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number BTB-501 found under Dry Base Printed Ci by Kepro Circuit Systems Inc. The National Stock Number assigned to this part is 3670010470885, and the Federal Supply Class is 3670 Specialized Semiconductor Microcircuit And Printed Circuit Board Manufacturing Machinery. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like BTB-501.