Review on Topeak Shuttle Gauge with Case, featuring an Air Pressure Dial by Tony Conlon

The reviewer who said it doesn't work with Presta valves is wrong. It comes with a Presta adapter and will inflate the Presta tires. BUT you cannot use the button to deflate Presta tires. Here's why: If the pin in the part that screws onto the valve stem was long enough to push on the top of the Presta valve, you wouldn't be able to unscrew it fast enough to maintain proper tire pressure. So you slowly add enough air to get the desired pressure and then stop. When you unscrew the shuttle or push the button, your presta valve closes immediately because it DOES NOT PUSH the PIN. Now tighten the top of the Presta valve and you are done. When you thread this device onto the Schrader valve, it gently pushes down on the Schrader pin and seals the valve stem. Inflate to desired pressure and stop. In the part that screws onto the valve is a check valve that prevents air from flowing back out of the tire. If you unscrew it, the Schrader valve closes before it breaks the seal, and therefore doesn't lose air. Shuttle is designed to be used with a manual tire pump. If you put a gas station air chuck on it, it won't push the pin into the chuck, which lets air through. You can get around this by fitting a replacement Chek A valve extension between the shuttle and cartridge. Accu-gage - Chek A Spare, Valve Extension By the way, if you've worn out the rubber o-ring in the presta adapter, you can replace it, it's number 008. When you screw it onto the presta valve, the O-ring goes first, leaving the threads on top. Some people get it the other way around.