Look at the arrow ....that pic is dated, when those first came out, like the string loop, they were originally intended to adress peep rotation. That is one of the first products introduced that was meant to eliminate the tubing to peep BS. There used to be a slo-mo video floating around that showed one of those flailing around after the arrow was released. String loops flail alot too, but are not as inherently dangerous as a piece of metal flailing out of control. It was soon after the introduction of several similar products that the string loop/D-loop came into existance.......now the choice of many...........I still shoot off the string, and consider that my best option. To each his own.