Factory Spec, K15771558520OBLK92, Black 520x92 O-Ring Drive Chain & 13/40 Sprockets 2001-2005 Yamaha Raptor 660 YFM660R All components are Factory Spec brand Chain has a tensile strength of 8200 pounds Sprockets are made of hardened steel and built to last O-ring style means it will last longer with less maintenance than conventional chains