Floyd Bell's M-80 Series, first developed, sold and launched in 1989 and redesigned in 1999, is a solid-state, environmentally secure miniature piezo electric alarm that is typically 20 dB louder and 1000 Hz lower in frequency than alarms of comparable size. Approximately 1 inch in diameter x 0.875 inches in height, it packs an explosive sound output of 103 dB at 2 feet. The M-80 pc mount and PM-80 panel mount piezo electric alarms feature an expanded voltage range of 5-15 Vdc. The M-100 pc mount and PM-100 panel mount have an expanded voltage range as low as 3-6 Vdc..