Safrone 5 Pieces Archery Arrow Nock LED Lighted Nocks Yellow for 6.2mm shaft(only light on by pushing them before shooting) Lightweight and precision-balanced for superior accuracy Indexed nock end provides added safety and easy ON/OFF design Fits any bolt with inside diameter 6.2MM Package includes 5 pieces lighted nocks Note: it's not activated while shooting.before firing your arrow,please put the battery pin into the nocks,it will turn on.On the contrary,it will light off.