The Ultra-Nok XL (extra long) is made to fit virtually all release aids. The Ultra-Nok XL is the only metal nocking loop that will adjust to fit all arrow nocks. Multi-position back plates adjust to fit the largest arrow nocks (11/32) to the smallest (G-Nock). The only metal nocking loop that extends to fit ALL release aids and has adjustable back plates to fit all arrow nocks. Unlike other metal nocking loops will not un-nock your arrow or dislodge arrow at let down. Will eliminate bowstring wear as well as align your peep sight. Has FOUR anti-vibration screws, not two, to keep the Ultra-Nok XL securely on your string without sliding, maintaining accuracy shot after shot!