The Upper Jackson Appliance was one of the original removable expansion appliances. Because it requires careful adjustment of the body wire, it's popularity has waned since the advent of the simple-to-adjust expansion screw. Still, when a differential amount of development is needed throughout the arch, the Upper Jackson is still an excellent appliance for the job. It can be adjusted at the body wire with 139 Bird Beak Pliers or at the acrylic extension with three-prong pliers. Lap springs control the anteriors, while the open palate promotes proper tongue position, thus helping to maintain lateral development.