This is an extremely well made mount that includes a custom cradle for your tablet.  All ports and buttons can be fully accessed.
An elegant solution that attaches to the car’s headrest posts. The mount consists of two core components, a high-quality universal headrest mounting pedestal and a custom fit holder.  Universal mounting: fits nearly all headrests with uniquely designed, laterally adjustable arms.  Complete 360° rotation for landscape and portrait viewing with 45° horizontal and lateral tilt.  Can be locked into position.  Custom protective holder fits your device for easy access to buttons and ports.

Note these only fit the original Samsung Galaxy Tab 7".  These do not fit any other model of Samsung Galaxy Tab.