Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 57-531 found under Hammer Hand by Stanley Tools Div. The National Stock Number assigned to this part is 5120010974520, 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 57-531.