Quick and Easy Installation: With no tools required, simply twist the knobs to quickly attach or detach the mount to most headrest posts (2” and 7.25” wide). Secure and Stable: Designed to keep the tablet stable and from bouncing while driving with the strong aluminum shaft. Tablet and Smartphone Compatibility: Cradle fits tablets with the bulkiest of cases and any other mobile device between 4 5” to 10” wide securely. Your Preferred Adjustability: Choose having your tablet directly behind a car seat for a single passenger or in between the driver and passenger seats for multiple passengers The ball-head also allows for different viewing angles and for 360° rotation. Kid Tested Parents Approved: Keep your children or other backseat passengers entertained on long drives drive in peace and avoid paying for expensive backseat entertainment systems.