The Helios RVM 400 is a motor-driven damper engineered to stop cold air from entering horizontal fan installations. It features a cylindrical sheet steel housing with flanges on both sides, enabling direct mounting to the fan base plate. Flange holes are drilled to match DIN 24155, page 2 specifications. The damper is equipped with lightweight aluminium flaps for reliable airflow control, while polymer buffer connectors ensure quiet, smooth operation. Supplied with a 0.9 m connection cable, it is recommended to wire the unit in parallel with the fan for synchronized performance.