This Flat Idler Pulley is for use as a general purpose pulley for power transmission such as compressors, industrial fans, lawnmowers, snowblowers and electrical motors. It comes with symmetrical bore adapters bushed from 17mm to 1/2'' inside diameter. 31325050 features a heavy duty sealed radial single-row bearing.This part is Painted Black to prevent rusting. Additional Features: Made of Steel Flanges angled outward to help increase belt life