Cool Attic CX2121 Automatic Gable Vent Shutter, High Impact One-Piece ABS Cycolac Frame, 22" W x 23" H x 3" D For use with CX1500 and CX1600 gable vents Not for use with VX2515SOLARGABL solar gable fan Louvers open automatically when ventilator is operating When ventilator turns off louvers close to keep out insects, rain and dust