We designed the Gravity model to be functional multifocus reading glasses for Mechanics. There are a few "car guys" at Sightline and we were tired of having our readers fall off while we were in odd positions working on our cars. The ratchet action temple holds the glasses in place no matter your head position.
These reading glasses are also remarkably strong. Fear not if you drop them, or toss them on your work bench. They are made of TR-90: