Nocturnal's Lighted Nocks feature an exclusive patented linear switch design that works every time with no wires or connections. The simple bowstring activated push on switch also easily switches off when no longer needed. These nocks have an extended burn time of 20+ hours, are waterproof and good for use in any conditions. Watch your arrow hit its mark under any light and find that arrow on pass thru shots. Bowstring activated linear switch Fool proof operation in any condition Long life lithium battery Super bright LEDs Water and weather proof Unsurpassed reliability Available in red,green,blue, and pink