12.5" Round. A unique plastic ceiling diffuser which incorporates an integral ceiling box. Intended for residential and light commercial applications, these products are currently available in 11-1/2” x 11-1/2” square and 12-1/2" diameter round. They provide maximum convenience and timesaving as they are designed for easy installation by one man only working from below the ceiling. Included is a built in Air Damper to restrict air flow when desired. Zip Tie Included. Used for a 4",6" or 8" duct.