Michelin's new Protek Max inner tubes are injected with sealant and have a square profile and textured bumps that react in compression if punctured. Michelin said this reaction helps the tube close around the hole. Regular inner tubes, by comparison, react in extension when punctured, opening up a larger hole, Michelin said. Protek Max tubes are available in 700 x 35/47mm in either Presta or Schrader valves. They retail for $12.99.
Source:
http://www.bicycleretailer.com/new-products/2013/01/29/michelins-square-inner-tubes
