Bluetooth Bone Conduction Sleep Speaker Smart Improve Sleeping

Product information:
Color: twilight gray, dark blue, pink
Frequency range: 100HZ-20KHZ
Charging mode: Type-c fast charging
Bluetooth version: 5.2
Product Size: 100*28*13(mm)
Built-in battery: 400mAh lithium polymer
Operating voltage: 3.7V-4.2V
Transmission Distance: 10 meters (barrier-free)