BikeMaster Handlebar Mirror Adapter Clamps - T4 (10mm) (Black) At BikeMaster, they understand the quality and performance that motorcycle owners demand. They also understand that quality should be affordable. Not just for professional riders and mechanics, but for the everyday rider / mechanic as well. That is why BikeMaster continues to bring that level of quality and performance to all riders with their complete line of tools, parts and accessories at affordable prices. This adapter allows you to fit a mirror to a bike without ugly sheet metal bracket.