Park Tool 2197 DT-5/DT-5.2 Diamond Abrasive Adaptor for Carbon Fiber. The 2197 is an add-on accessory for the Park Tool DT-5 and DT-5.2 Disc Brake Mount Facing Set to enable easier and more efficient facing of disc brake mounts on carbon fiber frames. Features a brazed-on diamond grit surface that is over 100 times more durable and effective on carbon fiber than the cutter included with the DT-5.2. The 2197 sits between the cutter of the DT-5.2 and the brake mount and smoothly and evenly grinds the mounting surface until it is flat and properly perpendicular to the rotor.