Renthal 254-520-13GP Ultralight 13 Tooth Front Sprocket All rear sprockets are made of 7075 T-6 aluminum alloy; select rear sprockets available in black Front sprockets are made of case-hardened nickel chromoly steel Ultralight front sprockets are 10% to 15% lighter than standard sprockets All sprockets feature self-cleaning grooves to clear mud and increase sprocket life Drilled design looks trick, saves weight and doesnt sacrifice strength