The rubber tubing shows your bow down, brakes and is just a pain in the back end. I have used them before and hated it. I have some friends tell that they have had them brake just as they drawled down on a deer costing a shot at a deer. I was at a shoot once and a buddy broke his and it was to short to repair in the field. It make his bow shoot about 8 to 9 inches high at 30 yards with out it. He went to his shop and checked his speed with and with out it and found out it was costing him about 8 to 10 fps.