These Ravin R123 replacement nocks are made exclusively for R500 and R470 series crossbows. High-impact Ravin-engineered polymer construction handles the massive forces these crossbows generate without cracking or failing. Clip-on design attaches securely to Ravin crossbow arrows without splitting the carbon shaft like press-fit nocks can. Makes field replacement quick and easy when nocks get damaged. These lock into Ravin's unique Trac-Trigger Firing System. You get consistent string release and straight nock travel for maximum accuracy. Precise fit prevents timing issues that can happen with generic nocks. This 12-pack gives you plenty of replacements for long sessions. Keep extras in your pack because nocks take a beating and will eventually need replacement. Bright orange color makes them easy to spot if you drop one in the field. Use only Ravin-branded crossbow arrows with these Ravin clip-on nocks for proper function and safety. Using generic nocks or arrows can cause timing problems and potentially damage your R500 and R470 crossbow's system.