Sort:  

oh, like the ones you use to watch a solar eclipse?

Like the ones fishermen wear. Polaroid is actually a brand, polarised is actually the correct name I suppose. A bit like Kleenex being synonymis with tissues. Any brand name and many crappy sunglasses are polarised and the effect is to reduce glare and increase contrast.

http://www.allaboutvision.com/sunglasses/polarized.htm