The Dot Line DL-0392 7" Articulating Arm have two nicely machined metal sections. The lower section has a locking accessory show mount. Or you can remove the shoe and use it with either a 1/4x20 female or male thread, so it fits any need. There is a ball joint on the base allowing it to swivel in most any direction. The top section also has a ball joint and a threaded 1/4x20 post.
The large knorled knob allows you to loosen both ball joints, top and bottom, move the arm into whatever position you desire and lock everything up with the twist of one knurled knob. Simple to use, yet extremely versatile design.