The check valve is intended for installation in round air ducts to cut air flow and prevent its return movement. The case is made of galvanized steel. The aluminum blades are spring-loaded, so the valve can be installed in an upright position.
Throttle valves are designed to regulate the flow of air and overlap of the round ventilation duct. The case of the product and the rotary blade are made of galvanized steel sheet. The adjusting handle is made of plastic.