Check the product on the QAD website and make sure everything that was supposed to be in the package is in the package.
The top containment arm is removable just for that reason. I don't find it necessary in any way. You would have to turn your bow almost horizontal before that top arm would come into play. If you have an arrow nocked and are moving your bow around, you're going to be holding the arrow with a finger so it doesn't clack around and make noise anyway. The HDX has anti-bounce on it, so even if over the shelf just add a bit of mole skin and you won't get that smack noise from it. Mine actually stops just shy of hitting the shelf.
HDX is on my Elite Ritual 33 and the Ripcord Max Micro is on my BT Allegiance ... never a problem with either ...
So apparently there’s a spacer that goes with this rest. Long story short, put spacer in and solved all my problems.
