Piezoelectric sounder at 109 dB. IP44 sealed electronics. Backup battery type NiMh 7.2 VDC (nominal) optional (not included). Top and wall tamper. Advanced microprocessor technology. Interchangeable polycarbonate case, available in a variety of colors (by default, white). Intermittent indication LEDs. Standby mode of the patented technician. Measures 189 x 186 x 60 mm. EN50131-1, EN50131-4 Grade 2 Class IV.