... design; built in rechargeable Specifications:Patented technology;Zinc alloy metal shell; small,portale and fashion design;DIY music;Strong BASS, ... 315 mini vibration speaker,1. Patented technology;Zinc alloy metal material shell;small,simple, durable,portale and fashion design; built in ... can drive any solid flat surface medium(desk,stone,glass,metal and etc.) to make sound according to the principle ...