The RACER PRO features Dynaplug original made-in-USA Twin Tube design. This allows you to store 4 pre-loaded plugs ready to go in a single tool. Snap-on caps protect plugs from dirt and damage. When you're ready to make a repair, just pop off a cap to deploy either a standard size plug (with wheel-friendly soft brass tip) or the aluminum Megaplug for mega-big punctures. If you need more plugs just unthread the Twin Tube and flip it around for more plugging action!