This V-Groove Idler Pulley is for use as a general purpose pulley for power transmission such as compressors, industrial fans, lawnmowers, snowblowers and electrical motors. It does not come with a bore adapter installed, the inside diameter is equal to the bearing diameter of 17mm. 345200 features a heavy duty sealed radial single-row bearing. Additional Features: Made of Light-Weight Plastic Works with 4L/A belts