Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 2N639B found under Transistor by Alpine Industries Llc. The National Stock Number assigned to this part is 5961008015471, 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 2N639B.