This Rope 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. 349000 features a heavy duty sealed radial single-row bearing. Additional Features: Made of Light-Weight Plastic Works with 0.28" diameter rope/wire belts