DO NOT FLY WITH NON POLORIZED LENS!
by doing so you trick your eye into opening wider because of the
shade. Remember polorization is used to protect from UV light. If
you open your eye wider by non polarized glass you expose your
eye to that UV light. You will damage your eye much quicker. It is
not a function of can you see your instruments or not. Do not be
mislead into this kind of thinking......
Most glider canopies are not made with polorized protection.