![EArch](https://www.johnsdental.com/wp-content/uploads/2016/03/EArch.jpg)
E-Arch
The E-Arch is a pre-activated fixed appliance used for mild posterior expansion. It consists of a .032 wire housed in a tube in the anterior, with a compressed Niti coil spring located on the wire between the solder joint and the mesial tube. The gradual decompression of the coil spring typically results in 3-4 millimeters of expansion.