I have a
TechMatte that I bought for my S5 (it got great reviews). Well, it works with the S7, HOWEVER, it also makes the battery do weird things, so I would stay away from that one.
Long story as short as possible. I thought my phone was having battery issues, even had it replaced at one point (same issue). Come to find out, it was the charger. If I didn't charge it up to 100% on the TechMatte, it would lose battery VERY fast (I'm talking 50% in a few hours). If I charged it up to 100%, it was fine. My phone didn't have that issue if I used fast charger that it came with. Can't wait to get my Samsung wireless fast chargers. Since it happened with two phones and two different chargers, I'm going to assume it was the charger and not a fluke.