Just screw Doohicki on chainstay bridge with enclosed hardware
When locating your pump behind seat tube, Doohicki will hold tightly bottom part of valve head of any of the following: alloy Zefal hp, hpx, Mt ZEFAL and Mt ZEFAL PLUS.
A clever 2-step stooper will prevent valve hole from getting dirt or water (first step is for presta, push down to second for Schrader.
