NAP Thunderglo Lighted Nocks have ultra bright LED illumination and feature an easy on/off feature. Thunderglo Lighted Nocks are crafted of a polycarbonate blend with an aluminum shaft making them extremely durable for long lasting use and life expectancy. Thunderglo Nocks comes in blue, green or red and are offered in a 3 or 6 pack. Universal collars will allow Thunderglo Nocks to fit most any arrow (G/X/H/S). For the ultimate in lighted nocks, trust the NAP Thunderglo.Polycarbonate blend Nock with aluminum shaftBright LED IlluminationAuto ON when nock is shotLED Stays ON until user unclicks the nockUniversal collars fits Arrow Shafts (G/X/H/S)Available in packs of 6