The Potter Amseco PAL328 Piezo Alert is an advanced electronic audible signal device that emits a compelling sound with minimum current draw. This solid state device operates from as little as 3VDC to as much as 28VDC and is rated at 20mA. Sound output is proportional to input voltages and ranges from a minimum of 68dB to over 100dB at 28VDC at 1 ft. The piezo electronic contact points give it high reliability and an exceptional long life. The piezo alert signal operates in free air only. It is not compatible with under water applications. The recommended operating range is from -13 degreesF to 158 degreesF (-25 degreesC to 70 degreesC). The PAL328 black Piezo buzzers operate when an audible frequency is applied from a transistor to an oscillator plate containing a piezoelectric element and metallic vibrating plate. Also known as -Amseco/Potter AMSECO PAL328 PIEZO W/ O NUT - AS-PAL328