The set consists of bite alarms, a receiver and a wireless bivvy light. The Bite alarms have six volume and sensitivity levels and six different tones. The wireless bivvy light works in conjunction with the bite alarms, illuminating and switching on for 5,10 or 20 seconds when a bite is detected. The Bite alarm requires one 9V battery (not included). The receiver requires three 1.5V AAA batteries (not included). The Bivvy Light can be connected via USB.