Widely Compatibility:The Car headrest holder widely compatible with devices from 4''-11'';opening width is up to 200mm,good for smart phones/tablet/etc Suitable for Most Car Headrest:The car headrest mount built-in stronger spring and press system ensure flexible stretch ,adjust it to fit for distance between 2 poles of most of car headrest 360? Free Rotation: Rotatable ball pivot ensure horizontal and vertical smart phone viewing,be convenient for use in car,hands free to enjoying movie,reading,video chat during road trip Dedicated For Road Trip:The car headrest mount is designed for keep tablets or smart phones be steady during car ride. The mount attaches firmly to the headrest posts of your vehicle.it is better to take off the case of cellphone or such things before use Quick use&Install:The car headrest mount can be easy to installed and used without tools