Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number HEF4000B found under Microcircuit Digita by Philips Semiconductors Inc. The National Stock Number assigned to this part is 5962014914979, and the Federal Supply Class is 5962 Microcircuits Electronic. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like HEF4000B.