... of sound FM Radio ,Headset Microphone ,Remote control 898A Waistband Amplifier Funtion:Peak Power output: 25 WattsFrequency response: 100Hz – ... 53 dBV/A +- 3 dBPower Source: Built-in Lithium Rechargeable batteriesBattery Life: 8-10 hours, 4 hour recharge, 2- ... working in 7-8 hourse Function Mp3, FM radio, Amplifier, loudspeaker, microphone, reverberation Application:Used for Yoga, Gymnastics, ...