Features of the Shimano XT RD-M8100-SGS Rear Derailleur CAGE LENGTH: SGS/Long MAX FRONT DIFFERENCE: 0 MOUNT: Direct attachment (conventional)/Direct mount compatible TENSION PULLEY BEARING: Sealed Bearing GUIDE PULLEY BEARING: Sealed Bearing NUMBER OF PULLEY TEETH: 13 SERIES: XT GENERATION: M8100 MAX LOW SPROCKET: 51 MIN LOW SPROCKET: 45 TOP NORMAL SPRING TYPE: Shimano Shadow RD+ REAR SPEEDS: 12