Exclusive patented linear switch design works every time, no wires or connections, simple bowstring activated push on switch, easily switches off when done, extended burn time of 20+ hours, waterproof, use in any conditions, see your arrow impacts under any light and find that arrow on pass-thru shots. The Nockturnal Lighted Nocks are designed for smaller diameter carbon arrows with an internal diameter of .246 inches, ensuring reliability and easy operation in low-light settings.