/ / / / we supply cross-roller ring series bearing, If you are interested, pls.contact us. Thank you./ / / / RA5008 RA6008 RA7008 RA8008 RA9008 RA10008 RA11008 RA12008 RA13008 RA1400 8 RA15008 RA16013 RA17013 RA18013 RA19013 RA20013 RA5008C RA6008C RA7 008C RA8008C RA9008C RA10008C RA11008C RA12008C RA13008C RA14008C RA15008C R A16013C RA17013C RA18013C RA19013C RA20013C Skewing Prevention The spacer retainer keeps rollers in their proper position, thereby preventing them from skewing. This eliminates friction between rollers, and therefore secures a stable rotation torque.slwing ring bearing, slewing bearing.