STFU Chain damping muduleMountain Bike Drivetrain Damping Module Includes two adjustable modules that mount to your swing arm + new profiled end caps for a more solid connection to the swing arm. Dual compound hard plastic insert keeps the unit stiff and in place with soft over mold for sound damping. Contains and controls chain slap so you can focus on the trail ahead Suits Trail Bikes with 1X gearing (single front chain ring) 9 13 speed with up to a 52 tooth cassette Dual