You can get 6-PACK LED nocks fit for carbon arrows with 0.244 inch/6.2mm inside diameter. Each nock only weighs approx. 23.8 grains. Constructed of an ultra-strong, impact resistant PC casting. String activated, illuminate immediately when the string is released. Matched with screwdriver make it easy to turn off. Any questions please email us. We will response in 24 hours.