Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number B9971-3.5 found under Ring Retaining by Hyco Inc. The National Stock Number assigned to this part is 5325012491661, 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 B9971-3.5.