The NGT Dynamic Wireless Bite Alarm and Receiver Set contains 3 bite alarms and a receiver all in their own foam padded ABS protective case. The Alarms have a range of settings for you to customise your setup to your preferred bite indication and a rolling code function avoids interference from other alarms. With a range of up to 150m you can be sure that if you move away from your rods you won't miss a bite. The alarm heads and receiver all require a 9v battery (not included).