Its something called xim 4 is what they use cost about the same as a scuff, I have a gaming pc so I know first hand How much of a difference it can make to someones game. 
I have seen a good few people on YouTube that are using them (they don't say)  but you can tell from how the reticle moves.
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	Lol yah the right arm is a dead give away. No one makes circles with one and not the other on a controller