Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 3503-K3B found under Retainer Turnlock Fastener Eject by Dfci Solutions Inc. The National Stock Number assigned to this part is 5325010437545, and the Federal Supply Class is 5325 Fastening Devices. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 3503-K3B.