- Takes place of rear wheel providing tension on chain to protect the frame when rear wheel is removed for cleaning, storage, or transport. - Allows full forward or backward rotation of drivetrain and shifting through full range of gears. - Quick and easy one-handed installation on standard QR style dropouts and removable pulley wheel works directly on 12mm thru axles. - Professional grade stainless-steel, aluminum, and solvent resistant plastic components ready for daily life in the wash bucket. The original Pedro's Chain Keeper has been a favorite in the wash buckets of mechanics for decades. The new Pro Chain Keeper carries this heritage forward to new levels featuring one-handed installation, shifting across all gears, professional duty stainless-steel and aluminum construction, a heavy-duty solvent resistant plastic pulley, and 12mm thru axle compatibility.