The Nockturnal FIT Universal Size Green Lighted Nocks offer a super strong clear polycarbonate construction that fits into an X arrow shaft. They come with sleeves (3 each) for H, S, and GT arrows and provide a 20 plus hour battery life. Comes in a three pack and provides a green light. Universal size fit Polycarbonate construction Fit into an X arrow shaft 20 plus hour battery life Come with sleeves (3 each)