[Nexus 6P Accessories] Elnrik:
See: http://androidandme.com/2013/12/opinions/why-i-dont-use-screen-protectors-an-engineers-perspective/

I know this is an old article, but it makes a point that is still valid. If you think about it, the two primary threats to the health of your phone's screen are 1) things that can scratch it and 2) impacts which will break/crack it.

When I originally read it, it got me thinking - If the only thing that will scratch my glass is something of equal or greater hardness, then just about any material covering the screen will protect it from scratches. Great! Super easy. The cheapest, thinnest, generic screen protector should work.

Impacts are a different story. I started researching impact physics and the characteristics of glass. Holy crap is there a metric crap ton of information to absorb concerning those topics. The few basic things I learned are this:

- Glass is very strong, until it isn't. You can apply force to glass and it generally won't deform or become damaged until you reach the magic breaking point.

- When protecting glass from impacts, you want to keep the force applied to the glass under this magical breaking point.

- Impact physics can be extremely complex. Think bullet-proof vests, newton's cradles, birds hitting airplanes, all of that stuff.

To over simplify it, there are only a few ways to provide impact resistance which are relevant to phone screen protectors. The first is to slow the velocity of the impact as much as you can, thereby lowering the force (or impulse) of the impact. Think of dropping a bowling ball onto a trampoline. The other is to redirect the force away from the point of impact, like a bullet proof vest does, so that the force which does reach the phone's glass won't exceed its breaking point. If you can combine both methods, great. Keep this in mind though: Because the screen protector is in contact with the phone's glass, some force will *always* reach the display.

From what I can tell, TGSP's are much more like the bullet proof vest example. The hard and brittle substance backed by a softer polymer and adhesive works to direct energy away from the impact site, and the act of shattering the TGSP itself absorbs some energy - energy which would otherwise reach the phone's glass. The problem is, TGSPs are expensive.

PET films are a bit more like the bowling ball and trampoline example. They slow impacts a tiny bit. They're much better at protecting from scratches than they are from impacts.

From what I can tell, the Rhino Shield protector layers hard and soft polymers in a sandwich, and combines the protectiveness of both examples. It's much stiffer than a PET film, but not fragile like a TGSP.

The ultimate problem is this: Just like the Newton's Cradle image above, because the screen protector is in direct contact with the phone's display, a majority of impact energy will *always* be transferred to the screen. None of these protectors will help you when that energy exceeds the magical breaking point. So, given that I can't protect the phone from all impacts, but I do want to protect it from scratches, I choose to use screen protectors. I also like the feel of glass over that of plastic. That is why I use a TGSP - but it's not because I think it will protect my display from shattering if I drop it.