Principle of bone conduction: Through high frequency and low density vibration Make a pleasant sound in the ear , healthier. Bone conduction speaker: I can give it to you anytime,anywhere Bring quality music experience. This is not a speaker in the traditional sense, it is not only for listening, but also for playing! Two tracks, True solid: IWS support, Bluetooth expansion to stereo 2.0 channel. Change the sound for the land Sound of all things: Bone conduction black technology, on different vectors, Sound amplification by high frequency and low density vibration. Product name:wireless speaker/bone conduction speaker Battery capacity:400 mah Power consumption:5W loudspeaker:3W/4ohm voltage:DC 5V/1A support:wireless + Frequency response:20hz-20khz Signal-to-noise ratio: equal 75dB Color:Black Material:ABS+aluminum alloy Package Contents: 1 * bone conduction speaker Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.