I've been wearing Tifosi sunglasses for almost 5 yrs.  I've had about 10 pair.  I personally am a big fan.  I've been wearing the Tifosi Slips for about two years.  I race Mtn bikes in Utah every summer.  The Tyrants were new for 2011.  I bought two pair.  I noticed that they were a bit heavier than the Slips i'd been wearing, but seems to be better built.  I found them comfortable to wear though.  I've got a small head and the slips fit really well.  So do the Tyrants.

After 21 races and countless hours of riding this year, here is the bottom line.  They do a really good of venting the sweat off the sunglasses.  I happen to have long eye lashes and they tend to fog up my glasses easily.  The Tyrants didn't fog up at all.  Depending on which pair you buy the come with three lenses or you can buy a pair with the phototec lens.  I have both.  I was pleasantly surprised that after all that riding they didn't have a scratch.  I must have dropped them at least a dozen times.  Tifosi Optics also has a good warranty.  I've used it once and they sent me a new pair no questions asked.  What they aren't is a nice pair of Oakley Sunglasses, but then again you are paying for the name.  I'd rather save my money and buy two pair for the price of one Oakley.