This product is way overpriced. Every one of the bike shops where I live sell them for $1 each. This will not allow you to use a tire pressure gauge. It only helps when filling up the tires with air. Also, I find that the adapters in general are annoying--when you unscrew them, the adapter will often unscrew the stem too. Then you are left to screw the stem back in and pump up your tires again. The very best option is to buy a bike pump that is compatible with both Shrader and Presta style valves. I got a fairly nice one at Wal-mart for about $20.