Abstract: An arm assembly with an arm locking system is described. The arm assembly can include a base to position the arm on a support structure, an extension arm, a height adjustable lift arm, and a head assembly adapted to receive an electronic display. The extension arm can be rotatably coupled to the base at a first joint, the lift arm can be rotatably coupled to the extension arm at a second joint, and the head assembly can be rotatably coupled to the lift arm at a third joint. The arm locking system can include a first lock, a second lock, and a third lock engageable to selectively prevent movement about the first joint, the second joint, and the third joint, respectively. The arm locking system can also include a fourth lock engageable to selectively prevent the height adjustment of the lift arm.