Mini Bluetooth SpeakerFEATURES: Turn Any Hollow Core Into a Speaker: This Mini Bluetooth Speaker is the smallest and most versatile bone conduction speaker in the world, allowing you to have a different but still great sound experience in any environment. Turn any void into a speaker anytime, anywhere. Different Sounds With Different Surfaces: This speaker uses bone conduction technology to give you a DIY sound experience. You can test and enjoy different sounds almost