The MAD Nano Bite Alarm Set Wireless 3 + 1 small but finely made! You ca not describe this alarm better. The MAD Nano Bite Alarm Set Wireless 3 + 1 is packed with features. Volume, tone and sensibility can obviously be adjusted. You can even set how long the LED should light up (from 10 to 40 seconds) by pushing the tone (T) button. Of course it features a 1to1 transmission and the reach is 100m. The alarm requires a small photo cell battery (MN21) and thanks to the sophisticated technique it will run for one season in average. LED colours: 3+1 red, yellow, green.