The Dayco Serpentine Automatic Belt Tensioner is designed to provide reliable performance and long life. This tensioner features a heavy duty cast aluminum spring case and arm to help resist cracking and fatigue, as well as thermoplastic rubber spring slot plugs and rubber O-ring seals to help keep contaminants out. Additionally, this tensioner has a steel pivot tube on specific designs for enhanced stability. FleetPride is your First Click in Heavy Duty®.