With the increasing use of serpentine drive belts on late model engines, more idler and tensioner pulleys are being sold Than ever before. Many of these pulleys are manufactured from molded plastic to reduce cost. However, plastic offers limited durability when Exposed to abrasive dirt, heat or when excessive belt tension is applied. All engine pulleys incorporate roller bearings that run at very high revs relative to engine speed. Increasing belt load and exposure to dirt or moisture accelerates bearing wear. All roller bearings used are from OEM manufactures and feature C3 rated high speed races, high temperature lubricant and heavy duty silicone seals for maximum service life at high RPMs. The combination of these engineering features at a very economical price has made CHENHUI the number one choice for overseas vehicle repairers.