When you shop a sunglasses, you should to know about her colour of her lens:
Blue or violet lens: estetic use.
Grey lens: recommended for to drive
Green or brown lens: recommended for outdoor.
Red lens: use recommended when ilumination is not strong.
Yellow and orange lens: use recommended for cloudy’s days.
Polarised lens: her purpose is protected the sight.
Reflection lens: use recommended for iluminated days.