The tablet holder is ideal for 7 to 11 inch tablets and connects to the Wheelchair Tube Clamp base via ball head through the S size (3") Super Knuckle Arm. The ball head on either end of the arm allows users to freely adjust the tablet’s angle and can be locked into position by tightening the central knob. The Wheelchair Tube Clamp is equipped with a ball head that directly mounts into the Super Knuckle Arm. The Clamp can be tightly mounted onto wheelchair frame tubes and provides a very stable base. Given that there is no universal diameter for wheelchair tubes, three plastic spacers and a rubber strip are included allowing the clamp to fit 3/4" (19 mm), 7/8" (22.2 mm), 1" (25.4 mm), 1-1/8" (28.6 mm), 1-1/4" (32 mm) tubes. It is recommended to leave the tube clamp installed on the wheelchair so that it does not need to be remounted. The Super Knuckle Arm is easily released from the Wheelchair Tube Clamp by loosening the central knob of the arm. This set mounts a tablet within a flexible 3" (7.6 cm) radius of a wheelchair tube.