Ideal-Air Portable Intake Adaptor
More products from: Sunlight Supply
This 12-inch ambient air adapter mounts on the back side of either the Ideal-Air 21,000 or 29,000 BTU commercial portable air conditioners.
It fits over the condenser to duct condenser air to the unit to improve cooling efficiency.
Comes complete with mounting screws.
Find the 21,000 BTU unit here, or the 29,000 BTU unit here.
More info from the manufacturer (PDF format)