Kelux PS4 thumb grips are a certified win. Any gamer looking to elevate their game and have better control over their thumb-sticks needs to invest in a set of these. You can get 10 of them, a set of 5 for only $9.99 on Amazon; http://amzn.to/1Svzvhl.
Each of the grips comes in a different height with each set having a different grip pattern on the top. Any gamer playing any FPS game needs to check these out. Not just first-person shooter games either, I have been using these for game like Fallout 4 and NBA 2K16 and I personally feel it is a better experience for those types of games as well.
If the tall grips are not your thing the smaller grips don't offer much other than giving the thumb-sticks a better feel (grip) when gaming. Especially after hours of playing when your hands are sweating, I felt I had better control over the thumb-sticks with the grips on them.
I also wanted to mention that even though these say they are for the PlayStation 4, I have tried them on my Xbox Elite controller and they worked fine on the Xbox controller as well. The tops of the PS4 thumb-sticks and the Xbox One thumb-sticks are almost identical in terms of size or radius of the top of the thumb-stick. So if you are not a PS4 gamer, but you are an Xbox One gamer these will work for you as well!