Surprisingly, it works
It's very simple, it has no locking mechanism to attach to the tube valve you want to inflate, and relies on a thich rubber o-ring about the width of a presta valve head. It can get up to 60psi before the pressure starts leaking, and up to 120 if you pump furiously to overcome the leak, but if you can hold it on with one hand and pump with another you can pump up to higher pressures.
This is the third right angle valve I've tried and so far the only one that's actually worked despite its simplicity.
Verified purchase: YesCondition: New