Replacement magnetic ring for PAS. Please choose left or right side. Warning: it is not possible to mount the PAS sensor on the other side. It is coded and can only be activated in one rotation direction. To change from chainwheel side to non-chainwheel side, you have to replace the mounting kit or unscrew the PAS sensor from its plastic holder and screw it in reverse direction. PAS sensor plastic holder replacement: The plastic part, where the PAS sensor is mounted with 2 screws.