Chain damper isolates the rider from spikes in the chains energy, reducing drivetrain feedback Engineered to smooth out peak chain forces by capturing a precisely calculated angle of rotation Multiple x-ring seals within the chain damper create maximum resistance to dirt and water Direct mount crank interface 7075 aluminum construction 230g Model Chain Damper Shimano Direct Ring Type Single Mount Shimano DM Teeth 36 Oval/Round Round Color Black/Silver Mount Type Shimano Direct Teeth Count 36T