Material: Galvanized steel sheet. Specification: Matches duct size.

Structure: Louver blades filled with centrifugal glass wool, back side covered with glass cloth and perforated plate with 5mm aperture, front side covered with galvanized steel sheet, featuring sound absorption and rainproof performance.

Sound attenuation: 10dB(A)

Pressure loss: 40Pa (air velocity 6m/s).