This is my 2nd pair of Serengeti Sunglasses & I love both.  The green Polar PhD 555nm lenses get the darkest of all the lenses that Serengeti offers.  I was concerned that the darker lenses would diminish the clarity in full sunlight but it doesn't.  Colors are vivid and the contrast is amazingly sharp.  Very light weight and the nose pads are very soft, comfortable and the frame seems very secure on my face.  Can't wait to wear these on my upcoming trip to Key West.