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