Arkon's HM00425MM car headrest mount pedestal is ideal for mounting a 25mm (1 inch) ball compatible device holder, pedestal, or adapter (not included) in the center of the back seat for use in taxis and other passenger vehicles. The aluminum pedestal measures approximately 2.4 inches (61mm) end-to-end and attaches with included Allen wrench to straight bar headrest posts on either the front or back seats.