Slime 30079 Super Thick Self-Sealing Smart Tube, Schrader Valve (20 x 1.75-2.125") Slime Super Thick Self-Sealing Smart Tubes are pre-installed with Slime Sealant and are thicker than the standard Smart Tubes, providing maximum puncture protection. Slime Tube Sealant prevents and repairs flat tires caused by puncturing objects up to 1/8-inch (3mm) in diameter. That means longer distances, faster times, and no flat tires. Slime Smart Tubes install like regular bike tubes and repeatedly seal punctures for up to two years. Designed to seal tread area punctures. Extra thick tube pre-installed with Slime Sealant to provide maximum puncture protection and prevent flat tires Instantly and repeatedly seals tire punctures for up to 2 years Valve type: Schrader Fits tire sizes: 20 x 1.752.125