Factory Spec, K16571691520OR94, Red 520x94 O-Ring Drive Chain & 14/37 Sprockets 2003-2004 Polaris Predator 500 Stock gearing for these models is 14/37 with a 520 x 94 chain Factory Spec brand sprockets are made of hardened steel and built to last O-ring style means it will last longer with less maintenance than conventional chains