Functions: 1. Bluetooth headphone 2. SD/TF card headphone (JH-212BT can only use TF card) 3. FM radio Specifications: * Fashionable and simple design * Hi-Fi stereo performance * Bluetooth Frequency: 2.4GHz * Speaker dimension: Φ40mm * Bluetooth transmission distance: less than 10 meters * Frequency range of the FM radio receiver: 76--108MHz *. S/N ratio: more than 90dB *. THD:less than 1% *. Frequency response: 20Hz -- 20KHz *. Power supply: 350mA/h chargeable Li-ion battery (built-in) *. Impedance: 32ohm *. Continous working time: more than 9 hours based on volume at 1/3 level *. Charging time: about 3 hours *. Sound of robot: beep *. Available for SD/TF card up to 16GB (the model JH-212BT can only use TF card)