Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 63-421D131 found under Grinding Machine Cylindrical by Cincinnati Machine Co. The National Stock Number assigned to this part is 3415000454875, and the Federal Supply Class is 3415 Grinding Machines. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 63-421D131.