I never used that exactly, but a few yrs back I had something, forget exact name called I think ZERO peep
it was a type of deal you had to center a bubble in a glass like level, same as this design more or less, but was just an add on to any set of sights
mounted to the bow riser where the sights mount
it was a royal pain in the ass to get set up, but worked to keep you in form, as it was designed to
but I didn't like it in low lights, and I found myself doing too much double thriple checking on every shot to get everything all just right
so I took it off
But I do think it does what it says if you do what your suppoosed to with them!