1 x 4 LED panels and troffers fit into 1-ft. x 4-ft. drop ceiling grids as part of new lighting installations or as replacements for fluorescent troffers of the same size. They use significantly less energy than fluorescent troffers and have built-in LED arrays so there are no light bulbs to install or replace. The 1 x 4 size is used to light narrow conference rooms, corridors, and other spaces that need a large amount of light but can't accommodate a larger fixture. Sometimes called flat panels, these slim fixtures are typically recessed into the ceiling so that the majority of the fixture is concealed for a clean look that doesn't draw attention to the fixture. The height of the panel must be less than the height above the ceiling for a proper fit within a recess.