This cool little adjustment tool comes in the kit and is only used to tension the belt. A good rule to go follow for any belt is not to over-tighten it. We started by tightening the belt and then checking the belt tension by turning the belt at the longest point. If the belt is adjusted correctly, it should twist less than 50 degrees. With this kit, our measurement was taken in between the crank and A/C compressor pulley. The next step was to make sure the alternator pulley was tight with a 3⁄8 impact gun.