The Gardner ATTa Underlit Bite Alarm is an ultra-reliable bite alarm with an inbuilt speaker, so it can be used with or without an ATT receiver on the bank. It is water protected to IP67 and powered by a single 476A 6 volt battery. The alarm is always on and ready for action, apart from when it is placed in its designated hard case, which is supplied. Bite detection works through a magnet roller wheel that is turned by line movement. The ATTa wheel detection system is intelligent: it understands where the wheel is and what the last activation was, which prevents false activations. ATTa heads are available in White, Red, Green, Purple and Blue. - Soft touch, non-reflective finish - Inbuilt speaker - High power transmitter - Intelligent bite indication - Low battery warning - LED driven wheel illumination - Betalight accommodation - Super strong fixing bolt - Ultra high snag ears - Adjustable sensitivity - Water Protected (IP67) - Protective hard cover - Full 1 Year ATT Warranty Sensitivity can easily be adjusted by fitting alternative roller wheels, which are available in a wide range of colours and in 2, 4 or 6 magnet configurations. The 2 magnet wheel makes the receiver beep once per 1cm of line movement, the 4 magnet wheel beeps once per 0.5cm, and the 6 magnet wheel is ultra-sensitive, beeping once per 0.33cm of line movement. To ensure the greatest reliability and longevity, clean and thoroughly dry the items off before storing them in a dry place. Gardner recommends keeping them somewhere warm, or at least at stable temperatures, to avoid heating and cooling that may cause condensation. If you are putting the buzzers and accessories away for extended periods, take out the batteries, as battery leaks are not covered by the ATT warranty.