"TPI Exhaust Fan Shutters are specifically designed for use with TPI commercial exhaust fans. U.S.A. Accessory Type Ventilation accessory, Material Type Aluminum, Dimensions L x W x H in. 3 x 45 x 45. Designed for use with TPI commercial exhaust fans Shutter blade and frame constructed from aluminum for long-term corrosion resistance Fits 42in. fans Air open, gravity close Features weather stripping for tighter seals"