If its for the 6 or 6+ I dont recommend a screen protector. The tempered glass are nice but the very small margin means the protectors are mae to just fit exactly to the edge of the actual screen without any overhang because of the curve on the sides. This means unless the install is absolutely PERFECT, you will have the edge actually a mm or so into your actual screen. I tried having them install it at the store (Geek Squad) several times, and none of the installs were perfect and things on the edge of the screen I could not accurately touch as the edge of the protector was there. I gave up eventually.
This was on my 6+. I had a 6 for a few months with no screen protector and never had one on my 5s either. None of them got scratched at all.
I recommend instead a case that has a holster where you can flip the phone around and slide it face in when not in use. Pure Gear has one...