Polarised Sunglasses

Polarised lenses are used in sunglasses to reduce glare from reflective surfaces such as the surface of water or the hood of a car. They accomplish this through a process called polarisation, much like a venetian blind controls sunlight through a window.  

While slightly more expensive than normal sunglasses, polarised sunglasses are invaluable in high-glare situations, such as driving, boating, golfing, surfing, and fishing.