Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number P55-27B found under Ring Retaining by Borg Instruments Inc. The National Stock Number assigned to this part is 5325002008845, 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 P55-27B.