Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 00553401 found under Extension Socket Wrench by J Blackwood And Son Ltd. The National Stock Number assigned to this part is 5120002437326, and the Federal Supply Class is 5120 Hand Tools Nonedged Nonpowered. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 00553401.