There are 3 main popular types of valves. The Presta (also Sclaverland or "fFench type") used mainly on road bikes, Dunlop, which is used typically on some city bikes and the Autoventil (also Schrader type) used on mountainbikes and, above all, cars.
Our tiny little thingy can help in your hour of need. When a puncture caught you on the side of the road and you have discovered that your minipump is not in you back pocket or it doesn't work, not all is lost. You can still reach the nearest petrol station and using this adapter, pump your tires up with a standard air compressor. Maybe you will never need it, but perhaps it will get you out of real trouble.