ENVISIVENT (CB5001) – PERMANENT MUD-IN FLUSH MOUNTED WALL AIR RETURN, 30” X 8” DUCT Designed as a permanent air return for walls Used to finish a standard duct opening of 30″ x 6″ (762mm x 152mm) or 30″ x 8″ (762mm x 203mm) Overall product dimensions 32″ x 10″ x 1/2″ (813mm x 254mm x 12mm)  Vented opening dimensions 27 ” x 6″ (705mm x 152mm) 48 directionally vented air slots Over 68 square inches (439 square cm) of open vent area Moisture, mold, and water-resistant Impact-resistant triple fiber reinforced cement board Machine beveled outer edges for seamless finishing Primed panels ready to accept paint Eco-friendly manufacturing and non-hazardous Can be installed on 1/2″ (12mm) or 5/8″ (16mm) drywall ENVISIVENT (CB5001) – Permanent Mud-In Flush Mounted Wall Air Return,