The Ultra-Nok II provides the ultimate, evenly balanced, release point directly behind the arrow designed to be used with shallow engagement release aids; including caliper releases. It stops the arrow from falling off the string. The Ultra-Nok II increases accuracy and consistency by improving arrow flight. Eliminates arrow pinching and bowstring wear. Unlike other metal nocking loops has four anti vibration screws to keep it from sliding up or down the string. Will maintain positive peep hole alignment shot after shot.