This assembly provide desk-top access to (19") control and monitor equipment. This model is 16-gauge CRS and include one pair of mounting rails, tapped 10-32, hardware and wiring access below rear door or panel. The 400-12 includes locking rear door with spring-loaded hinge, side vents and optional front door with self-tapping screws. Inside (usable) dimensions are 17-3/4" W x 14-1/8" D.