Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 20C13-51 found under Screw Machine by Eastman Machine Co. The National Stock Number assigned to this part is 5305015025976, and the Federal Supply Class is 5305 Screws. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 20C13-51.