A plate assembly includes upper and lower plates. The upper plate has down turned inner and outer edges receiving inner and outer edges of the lower plate. In this manner lateral shifting is facilitated. The upper and lower plates have upturned left and right side edges. Left and right outer supports have upper ends slidably received on the upturned left and right side edges. The outer supports have lower ends positionable against a region beneath a sill of a window opening. A support bar has a central section attached to the lower surface of the lower plate adjacent to the inner edge. Telescoping sections are slidably received in the central section. The telescoping sections have forwardly extending clamps.