Replacement Gates brand 3.5″ flat idler pulley with ribbed flanges on the side to hold the belt alignment. This pulley is for 6 rib belt setups that run on the flat side of the belt. 17mm center ID
To measure the size of your pulley, measure the diameter of the pulley where the belt rides. If your pulley has flanges, you will need to remove the flange distance from your measurement.
As of 10/25/23, we will start putting models of confirmed kits, that use this idler.
1997 BMW E35 M3 Powerdyne Kit- this is the idler belt tensioner for the supercharger,