Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number K21-16320-00BLK found under Bolt U by Klinge Corporation. The National Stock Number assigned to this part is 5306016321794, and the Federal Supply Class is 5306 Bolts. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like K21-16320-00BLK.