Ravin Replacement Nocks - High impact Ravin-engineered polymer nocks are designed to lock into Ravin’s unique Trac-Trigger Firing System. Ravin Replacement Nocks come in a set of 12 and fit all Ravin branded arrows EXCEPT the R500 Series. Features Set ff 12 High Impact, Ravin-engineered Polymer Use Only Ravin-branded Arrows With Ravin Clip-on Nocks Not For use in Ravin R500 Series