Wolf Tooth Components 40t 130bcd Drop-Stop Chainring Black Not compatible with 9 speed chains Made from 7075 Aluminum for long life For maximum retention, utilize with a clutch-style rear derailleur If riding in extremely muddy conditions, Wolf Tooth recommends a chain guide or chain keeper in addition to a clutch-style rear derailleur Optimized for use with 10, 11, and 12 speed chains