Aprilia RS 660 2020> SITTA 520 Pitch Rear SprocketCentering holes : 100 Distance between holes : 120 Holes number : 5 Holes diameter : 10. 5 Remember to select the characteristics of the desired crown in the overlying drop down men. Full sprocket made from solid aluminum by CNC machining. These sprockets are used by the best MotoGP and Superbike teams, in fact thanks to the experience gained on the track Sitta has reached very high levels of precision and quality of materials. To mount this product