Ths ARS LSA Belt Tensioner is fabricated from 6061-T6 billet aluminum and is designed and engineering using custom springs, hardened steel shafts, and bearings. This is a direct bolt-on replacement for the stock tensioner for the GM LSA supercharger drive. With 60lbs of spring tensioner, it is 20% tougher than the factory tensioner. When purchasing, please choose your pulley from the drop down menu. All components are anodized, providing a hardened finish for protection and to minimize belt wear. A ceramic bearing upgrade is also available.