They were a great fit to the bolts the only thing was when I shot the crescent exploded no damage done to the bow or arrow my dad will be shooting one later tonight to see if the same thing happens

Seem like they are a better design than luminocks.

These work great! Would like to see a "strobing" nock for bolts.

The rubber "O" ring that prevents the knock from turning on do not last long and are not available as a separate part. The rubber "O" rings rot after a period of time and cause the knock to light when not in use. The expensive lighted knocks then burn out and become useless as intended.