All brands of replacement automatic belt tensioners are not alike. Automatic tensioners that are specifically designed for the unique packaging & operating conditions of each engine & accessory belt layout configuration (‘application specific’) are recommended & highly preferred. When properly designed & applied, these belt tensioners will provide pre-determined (‘engineered’), constant tension & variable damping to the belt. The engineered output of these tensioners consistently maintain correct belt tension and help to dampen belt system vibrations, within the belt's replacement life.