Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number KR520-17 found under Bearing Sleeve by R G Rollin Co. The National Stock Number assigned to this part is 3120013454610, and the Federal Supply Class is 3120 Bearings Plain Unmounted. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like KR520-17.