Product Details: Get your semi Ready for the Road Ahead™ with a quiet belt that generates stable electricity, with the Dayco 1.1" x 63" Poly Rib® Heavy Duty Serpentine Belt. By working alongside multiple tight pulleys and the alternator, this replacement belt works to convert the mechanical energy of the engine into electrical power for accessories. Built with advanced EDPM rubber materials to reduce how often a belt should be changed. FleetPride is your First Click in Heavy Duty®.