the usefulness of lenses

Rest, as signaled by several other critics, the magnification 0.7 useless. Simple flat glasses were more than enough to replace the lenses (which I removed several times according to the method written here: a screwdriver and hop is done in 2 minutes flat).

And this question unanswered: why 18 euros for a piece of plastic?

Anyway, I'm satisfied with my purchase delivered in a timely manner (Amazon Prime, it's really good actually).