When boxes are installed before drywall they sometimes are not mounted correctly which causes the box to be set too far back from the drywall not permitting the device to be installed properly. The box extender levels and supports a wiring device when the box is too far back from the wall surface. Adjusts to 1" to 1-1/2" and functions with all standard devices, switches, and GFCI's. The box extenders can be easily trimmed for adjoining multiple gang boxes.