I'm not sure if I've been completely shadowed from the market recently but I've just noticed within the past few months that glass screen protectors are getting quite popular. For those of you that own one: what one is your favorite? What is the difference between them and typical screen protectors like Invisible Shields? How in the world are they installed? Thanks to all of you in advance! I am really interested in them but don't want to end up making a poor choice in switching to them.