Hi Everyone, I want to purchase to Magnesium Sunglasses. I have never owned any pair of Mag's before, so I would like some advice on what is best? M-Frame Magnesium Mag Switch Mag Four S So here are my Questions: Are there any other Magnesium Models? What do you recommend out of the 3 that are shown. Are they made of Metal or Plastic? And can the Four S fit Adult Head because I heard its small. Thanks!