These tubes are more than twice as thick as standard inner tubes to help resist punctures. If flats have been a problem give these a try. Find the correct size for your bike from the drop down box below. These tubes come with a conventional schraeder valve and are sold in a package of two. Tire Reference Sizes Mtn Bikes - 26 x 1.25/2.25 Road Racing - 700 x 18c / Hybrid/Cross 700 x 24c Ten Speed - 27 x 1.25 / Three Speed - 26 x 1 3/8 BMX - 20 x 1.95/2.125 / Juvenile - 16 x 1.75 / 12 x 2.125 Availability: Usually ships the same business day THORN RESISTANT BIKE INNER TUBE - 2 PACK (s)567.253Regular price: $20.99Sale price: $17.49Size: 12x2.12516x1.520x1.9524x1.526x1.3/827x1.25