The airflow direction of a single-layer louver air outlet is one-dimensional, either horizontally left-right or vertically up-down. However, the airflow direction of a double-layer louver air outlet is two-dimensional, featuring both horizontal left-right and vertical up-down directions.

Typically installed on pipelines or side walls as side supply air outlets. The double blade damper has two adjustable blades that can change angles. The shorter blades are used to adjust the spread angle of the supply air flow and can also alter the direction of the air stream; adjusting the longer blades allows the supply air flow to adhere to the ceiling or tilt at a certain angle (when supplying warm air). The outer blades of the double blade damper or the blades of a single blade damper can be aligned parallel to the long side or the short side, and the choice can be made according to the customer's requirements.