Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 3-13-31 found under Screw Cap Hexagon Head by Hutchens Industries Inc. The National Stock Number assigned to this part is 5305010996438, 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 3-13-31.