1.Max Sound Output: ≥125db
2.Max Sound Gain: 50db ± 5db
3.Harmonic Wave Distortion: ≤ 3% (AT 1000 Hz)
4.Input Noise: ≤ 30 db
5.Frequency Range: 300Hz ~ 4500Hz
6.Working Voltage: D.C 1.5V
7.Working Current: ≤ 4 mA 8.Battery: AG13 or A675
Adustement,USA Knowles speaker