MICHELIN's Airstop name says it all. Their Airstop tubes use a proprietary butyl rubber that holds pressure longer so you won't have to top off your tires so much. These fine tubes are reinforced at the valve, too.
Schrader valves are identical to those found on car tires. These valves are generally used on hybrid and children's bikes. Presta valves, which are found on most road and off-road bikes, are longer and thinner and feature a threaded tip, which must be opened to inflate (turn counterclockwise).
Size: 29 x 1.9-2.125-inch