Park Tool バルブコアツール (VC-1)

This little tool fits perfectly in my jersey pocket, and the built-in wrench flats make extending Presta valves effortless. The knurled grip gives plenty of control even with sweaty fingers.

I’ve had trouble with cheap valve tools stripping before, but this one’s machined metal tip grabs Presta cores firmly every time. The built-in wrench flats make removing valve extenders a breeze too.

Finally, a tool that actually fits both Schrader and Presta cores without slipping. I used it to remove a stuck Presta extender and the 5mm wrench flats made it easy. This thing is tiny but does exactly what it's supposed to.