Electronic Air Pressure Head Massager, Relaxed Music Helmet Massager, EU Plug 1.Air pressure music massager makes you feel more comfortable. 2.The massage contacts is made of premium rubber and shape of nail, which is soft, so you can feel more comfortable when you using. 3.The shell is made of ABS, which is wear-resisting and not easy to be dirty. 4.Two ways for charging: -Power outlet -Four sections AA battery (It does not include when shipping.) 5.Method of application: -Wear feel free According to your head size, you can adjust the distance between the top and both sides to a suitable state and then put the massager on your head. At the same time, you should adjust the degree of light shade of the top and then adjust the top distance suitably. Using the rotary button of the side to adjust: (1) The biggest inside diameter: 68cm The smallest: 54cm (2) The biggest outside diameter: 77cm The smallest: 69cm Suitable head size: 54-68cm