I had bought these vent clip types of Cell Phone holders in the past, and they all failed after getting hot in my car. They'd loosen up and fall off, very annoying.
I bought a Bracketron suction type holder that attached to the windshield, and my phone got so hot, it wasn't good, but it stuck and stayed in place fine. I tried moving it from the side window my car has and the suction finally failed, (I've had that one for about 3 yrs!)
I had to replace it, but didn't want another windshield mount. My car doesn't have a smooth enough surface besides, the windshield, to attach another suction type holder, so I decided to try another vent mount one.
This holder is great, due to the brace at the bottom, it doesn't bounce up and down, and the clips are very sturdy! It's very secure while I'm driving, keeps the phone cool, and the clamps holding the phone work better, glides open and close much better than the older Bracketron TripGrip! I really like this one!!!