This is a beefy all metal Tablet Adapter from Ulanzi.  These are very nice.  At 8 oz. they are heavier than you might think, and when fully open they are quite large.  There is a ¼-20 thread in the base.  The range of the adapter is from 5.25 inches to 9.75 inches. We use these in our tablet rigs mounted on the end of a Positioning Arm.  We recommend anyone attaching a tablet to a backstop also use the safety tether for a second connection.