PERFAIR-RT plenum with top connection for PLAY rectangular diffusers. With built-in perforated damper + air equalizer, or choice of cable-operated dampers. Incudes anti-seismic tabs and crossbar with long screw and white cap for face attachment. For 48″ x 12″ faces, with choice of 6″, 8″, 10″ or 12″ neck diameter. Made by EffectiV.