I am vonsidering adding a Mars to my collection. I've never handled a pair, let alone seen one. How is the build and fit comfort, as I do like to wear my small collection. As far as replacement pieces, rubbers, gaskets, etc...are they easy to obtain. I think I have noticed on ebay that they use a c gasket of some sort? And, last but, not least, is a T6 driver the tool to use to replace lenses if need be?