Tire liners shield against punctures from thorns, glass, and road debris - the nemesis of every cyclist. Made of durable, lightweight urethane, Mr. Tuffy provides an additional protective layer between the outer tire and inner tube. Adding these liners to your bike, in addition to the built in K-Shield tire liner of the Kenda K-Rad tire, you’ll have a bike that’s ready for the toughest of roads.