These 5PCS LED archery tail lights are designed for 6.2mm arrow shafts. With a long-lasting non-replaceable battery, they automatically light up after shooting. Made of durable polycarbonate material, the press-in-fit design ensures easy installation. The string-activated switch prevents accidental turn on/off. Enjoy improved accuracy and ease of retrieval with these luminous light nocks. Package includes 5 arrow nocks with batteries. Perfect for hunting and archery enthusiasts. Features: - Fits all arrows with inside diameter 6.2mm carbon shafts. - Battery (non-replaceable) last over 24-48 hours(battery included). - Automatically lighted after shoot,you do not need use hand to light it first - Insert the nock into shaft,align it to your desired position and you're ready to shoot. - Constructed of a super tough polycarbonate material with a press-in-fit design. - After arrow retrieval simply push back activator switch located in side of nock to the off. - The nock has a string activated linear switch that is housed within the nock and will not turn on or off accidentally. - Their double-snap throat with special string angle compensation keeps arrows on the bowstring, even at extreme angles and with string loops. Specifications: Material: ABS Length: 45.5mm Package Included: 5 x Arrow Nocks(battery included) Notes: 1. Manual measuring, please allow 1 ~ 3mm error, thank you. 2. Due to the difference between different monitors, the picture may not reflect the actual color of the item. We guarantee the style is the same as shown in the picture.