Slime Smart inner tubes are self-healing for an extra line of defence when cycling on the morning commute or through winter months. All Slime cycling inner tubes are pre-filled with a precise volume of Slime Tube Sealant. This sealant seeks out and seals punctures as they happen. That means preventing flats, sealing instantly, repeatedly and continuously. With Slime tubes you dont need to worry about spending time repairing flats. Key Features: Seals punctures up to 3mmEnvironmentally safe, non-toxic, non-hazardous, and water solubleInstalls easily, works continuouslyDoes not freeze or dry up, lasts for up to 2 yearsSchrader & Presta valve available