Item: Roof Curb,Type: Fixed, Nonventilated,Curb Height (In.): 12,Curb Square O.D. (In.): 71,Curb Square I.D. (In.): 68,Flashing Flange (In.): 2,Mounting Flange Surface W (In.): 2,Construction: 18 Gauge Galvanized Steel,Use W/Dayton Ventilators Having A 72-1/2" Square Base,For Use With Flat Roofs Only,Weight:230 Lbs, In Bulk, Made in USA.