1. It conform to national standrad GB8108-1999. 2. Tone charactor: Siren, fire, tool, wail-2, yelp, hi-lo, wail-1, horn. 3. Handhold mike with control mike. 4. Monolithic integrated circuit in steadier performance. 5. Technical data: Voltage: 12V/24V Power: 100w Impedance: 8 Sound compression level: 120-130dB