Here's another Serengeti fan.Using them for over 4 years now.
The difference between a Serengeti and another pair is that you may add one thousand metres to the reported visibility with the serengetis.Literally.
Great for landing into the sun on a hazy winter morning.
The best site for them was
http://www.serengeti-eyewear.com/, (i just got a replacement temple from them), altho' they are modifying the site for the time being.