[Compatibilities]Keuaaao X lighted nocks fit arrows with .204 Inside Diameter, bushings matching and easy installation [Brightness]These arrow nocks emit a vibrant and highly visible light, making it easier to track your arrows, the winter holiday season, visible in darker evenings, help watching trajectory, enhancing accuracy and retrieval [Easy On/Off]The light come on automatically when fired, and slider switch to shut off, bowstring activated linear switch so easy [Battery Life]Great battery life of LED lighted nocks: Up to 48 hours, the light is very bright even in midday sunlight [Practicality]These lighted nocks for arrows are excellent for archery hunting target shooting in the winter, in darker evenings, in bright daylight, even 3d tournament, help watching trajectory and find the arrow. They are a fantastic addition for any archer seeking enhanced shot visibility Colour: Blue / Red / Green Material: Plastic Package Contents: 12PCS x Lighted Nocks for Arrows Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.