A tensioner pulley is a device that can be used to tighten the belt in the system of belts or chains and pulleys.The system typically consist of a number of wheels known as pulleys and a belt that is wound around them. In order for the belt(chain) to fit around the pulleys, some part of the system needs to be adjustable. One way to allow for this type of adjustment is a tensioner pulley, which can be either manual or automatic. Manual tensioners usually are pried into place or adjusted by turning a bolt, and automatic tensioners typically are spring-loaded.
G&W offers total 77 types tensioner pulleys,they can be applied for the most popular European cars.