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. Forget the rubber O-Ring style plug sockets which get oily and worn out. These magnetic sets will make removing or installing plugs in modern twin cam engines a breeze. Will not wear out over time like the O-Ring type. Includes 16 mm (or 5/8"), 18 mm, and 21 mm (or 13/16").