I don't know anything about it. However, I would not want to buy one for ever bow I own. I would rather learn to get the proper grip.
I recently started shooting a Timberline NO-PEEP for hunting. I have been absoluted amazed at the repeatability of the thing. I shows me when I am torquing the bow and also when I am making a variation in my grip.
I was really quite amazed at how much variation there was. I think it will make me a better target shooter. Since I don't use a clarifier, I may even try it on a target bow.