Roof Curb, For Fan Base Size 25 in to 30 1/2 in, Curb Height 12 in, Curb Inside Width 19 1/2 in to 28 in, Curb Outside Width 23 1/2 in to 32 in, Material Steel, Standards UL 705, For Use With 25 in to 30 1/2 in Square Base, Adjustability Adjustable,...