As of last week, I upgraded from a cracked, partially missing screen on my Iphone 5c to the Iphone 6s. I was super excited to actually read my screen!! When I was at the store, I was strongly advised (probably from the looks of my old phone) to purchase a glass screen protector. The salesman said the glass was designed to take all the force if one were to drop their phone. He said the glass was similar to that of what the military uses (for what, I do not know). I am curious what properties of glass alter it's durability. Or other questions come to mind as well: if any glass is layered on top of the phone, will it protect it just as well? I also wonder how the force protects the actual screen from cracking. I hope the screen does it's job because with my track record, I'll have my phone shattered in a few months. On the plus side, even though the screen costed me $40, there is a lifetime warranty!