Good idea, if only it worked.
It is a good concept, but fails in execution. The screw-on Lezyne chuck head is cumbersome to install and remove from a presta valve, but it does provide a good seal. This slip-on chuck head installs readily, but doesn't hold on very well, and pops off too easily, even when inflating fairly low-pressure mountain bike tires (60 psi). It was only $10, so I'll consider it a lesson learned, but I took it off and went back to cumbersome (but effective).
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