Mill Finish Aluminum, Slant Back Roof Vent, Flashing Dimensions 16-3/4" x 18-3/4", 9-1/2" Opening Fits Between 16" On Center Rafters, 50 SQIN Net Free Area, 8" x 8" Aluminum Screen, Will Ventilate 94 SQFT, Louvered On 3 Sides For Maximum Air Flow, Fits 3/12 To 10/12 Roof Pitches.