1. Input terminals: DCФ3.5DC Plug 4   2. Working voltage: 3.7V   3. Maximum output power: 90MW   4. Noise level :18db   5. Signal to noise ratio (SNR): ≥ 90db   6. Power supply: 600mA  lithium battery   7. Rated operating time:≥28h   8. Noise Reduction Type: One-way feedback  9. Speaker diameter: Ф40mm   10. Speaker Impedance: 32Ω   11. Speaker frequency response: 20Hz - 20KHz   12. Speaker sensitivity: 115dB   13. Wire length: pvc wire, 1.2m