Rage Hypodermic Crossbow high energy shock collars prevent the blades on your Rage Hypodermic Crossbow broadheads from prematurely deploying if you happen to bump your arrow or broadhead while on stand or stalking. High energy shock collars are designed to break upon impact and will need to be replaced after each shot. Blades should rest on the solid portion of the shock collar, not in the cuts. Inspect the shock collar for any damage prior to use to ensure proper function. Approximate quantity is 15-20 per container.