With this, you can mount your RMR on the objective side or eyepiece side of you controls (depending on the length of your scope). I have it on my AR mounted Nikon AR scope. I don't feel like I have to adjust my cheek weld position much transitioning from the scope to RMR.
Pros: Allows complete versatility on a custom positioning
Cons: price point
This review was written in the old system and had content requirements that are different than reviews written today.