Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 31603 found under Tap Thread Cutting by Industrial Supplies. The National Stock Number assigned to this part is 5136016005288, and the Federal Supply Class is 5136 Taps Dies And Collets Hand And Machine. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 31603.