Curb Cap For Fan Diameter 18 in For Fan Type Tubeaxial Mounting Hole Diameter 1/2 in Material Steel Body Diameter 26 in Bolt Circle Diameter 18 1/2 in Compatible Curb Grainger Part Number 2RB79 4HX41 4HX49 Finish Baked Enamel For Use With 4C661 4TM82 4TM83 Maximum Inlet Air Temperature 200 Degrees F Metal Material Thickness 3/8 in Overall Height 6 in Overall Length 30 in Overall Width 30 in Product Type Curb Cap