Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number P21B found under Ball Bearing by Correct Mfg Corp. The National Stock Number assigned to this part is 3110001006186, and the Federal Supply Class is 3110 Bearings Antifriction Unmounted. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like P21B.