Bone conduction: This under pillow speaker can transfer the audio via the bone, so it won't easily disturb others while working.Long work time: Built-in large capacity polymer battery, this wireless loudspeaker can provide 20 hours of music playing time and has 300 hours of standby time.Easy to connect: Support bluetooth-compatible 5.0, this under pillow subwoofer is easy to connect with most types of phone and tablets.Auto power off: This bone conduction wireless speaker will turn off automatically after 30 minutes, so you don't need to turn it off manually while sleeping.Other function: This under pillow sound box supports a memory card, which allows you to play MP3 music directly from the memory card.Specification:Bluetooth-compatible version: 5.0.Connection range: Approx. 10m/32.81ft.Material: Plastic.Working voltage: 3.7-4.2V.Vocalism unit: Bone conduction.Frequency response range: 40Hz-20KHz.S/R rate: 75dB.Battery: Polymer battery, 400mAh(Built-in).Music play time: About 20 hours.Standby time: About 300 hours.Charging voltage: 5V, 400mA.Charging time: About 2 hours.Size(LxWxH): Approx. 15.5x3.6x1.2cm/6.10x1.41x0.47 inch.Channel: 2.Audio crossover: Full-range.Input power: 25W.Rated power: 4W.Impedance: 2.Sensitivity: 32dB.Total Harmonic Distortion: 1%.Note:There might be a bit of color distortions due to different computer resolutions.There might be a slight error due to different hand measurements.Package Includes:1 Piece Speaker(with 1 Piece Charging Cable, 1 Piece User Manual).