I had one in the past. Never understood what the heck it did. All my bows are without them now. All they do is get in the way imo
I don't currently use one.... However I think I will be putting one on soon. I think they are to "catch" your bow at the shot. I have noticed lately when I shoot it tend to "grab" my grip the same time I am squeezing off the shot. Seems to be affecting my accuracy.