Complete Serpentine Kits make it easy to restore the entire accessory belt drive system. Neglecting to replace the tensioner and pulley(s) at the same time you replace the belt can ultimately shorten the life of the belt as well as other front-end accessory components.
Service Tip: Always replace belts and tensioners together. Old tensioners will reduce a belt's lifespan, and can lead to issues such as overheating, a dead battery, diminished power steering, or poor air conditioning performance.