Intake C-SeriesModel C416 - Mill Finish Companion product for all types of exhaust vents. 25 square inches of Net Free Area.Model C416 - White Companion product for all types of exhaust vents. 25 square inches of Net Free Area.Model C416 - Brown Companion product for all types of exhaust vents. 25 square inches of Net Free Area.Model C616 - Mill Finish Companion product for all types of exhaust vents. 37 square inches of Net Free Area.Model C616 - White Companion product for all types of exhaust vents. 37 square inches of Net Free Area.Model C616 - Brown Companion product for all types of exhaust vents. 37 square inches of Net Free Area.Model C816 - Mill Finish Companion product for all types of exhaust vents. 65 square inches of Net Free Area.Model C816 - White Companion product for all types of exhaust vents. 65 square inches of Net Free Area.Model C816 - Brown Companion product for all types of exhaust vents. 65 square inches of Net Free Area.CR-8 - Brown Provides an outlet for air movement in small confined spaces. 13 square inches of Net Free Area.CR-8 - Mill Finish Provides an outlet for air movement in small confined spaces. 13 square inches of Net Free Area.CR-8 - White Provides an outlet for air movement in small confined spaces. 13 square inches of Net Free Area.