Description: The luminous light makes it easier to see Lightweight and precision-balanced for superior accuracy Piston switch and easy ON/OFF design Waterproof and shock resistant design, Plastic nocks and stainless Pisiton Shot placement recognition and arrow retrieval. Indexed nock end provides added safety. Adjustable barrel end is easy to install and provides reliable performance fit. Press the metal parts, it will turn on when the circuit connected. If you want to turn it off, pull the metal parts for circuit disconnection. It is mechanical, please turn it on before you shooting. And it can't turn off automatically. Turn on and off easily Same plastic color as the light Specifics: Note: the battery can be replaced Color: As the picture show Material: plastic Fits any bolts with inside diameter 6.2MMincludes:1 x light nocks