Mr. Tuffy prevents puncture flats. When placed between tire and tube, it provides a protective layer between road hazards and the inner tube. Thorns or glass that may penetrate the tire are blocked from the inner tube. Proven Tough - For over three decades Mr. Tuffy has been the world's leading flat-tire preventive with Millions upon Millions of satisfied cyclists. Lightweight - Weighs less than liquid fills and thorn-resistant tubes. New Ultra Lite weighs even less. See right. Easy Installation - No gooey mess. Absolutely, Positively - Will not cause tire or tube damage-or loosen spokes. Mr. Tuffy Tire Liners are available to fit any size tire.