Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 9000423-21 found under Lamp Incandescent by Singer Co The. The National Stock Number assigned to this part is 6240009273180, and the Federal Supply Class is 6240 Electric Lamps. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 9000423-21.