Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 56-31221-20 found under Cup Tapered Roller Bearing by Electra Motors Operation Power. The National Stock Number assigned to this part is 3110001000586, 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 56-31221-20.