The damper is made of a black steel coating with thickness of 3 mm and 2 valves with thickness of 6 mm that are attached to the rollers with thickness depending on the damper size. The rollers' rotation mechanism is enclosed in a box sheltered on two sides with a perforated metal sheet. The box is at a distance from the damper in order to limit the medium temperature influence on the operation. One of the rollers is extended beyond the box and an electrical actuator that controls the rotation is mounted on it. The actuator is controlled by an electrical voltage signal 0..10 V. The damper opening is controlled from 0 to 100%. The maximum medium speed should not exceed 22 m/s. The damper is adapted to operation with flue gases with a temperature up to 200 °C.