The name Airstop says it all. Michelin's Airstop tubes use a proprietary butyl rubber so your tires keep their pressure longer. And, the reinforced valve stem seam is ultra sturdy, too.
These tubes have smooth stems. If you have a Silca pump which relies on a rubber gasket with a compression seal, these will ensure that the gasket lasts a lot longer. As far as I can tell, they also work fine with other kinds of pumps as well.
