The Soler and Palau PER-400 W plastic louvre back draught shutter is designed for 400mm ventilation systems. Its louvre design permits efficient airflow while blocking unwanted reverse air movement when the fan is off. Made from durable plastic, the PER-400 W ensures long-lasting performance and protects the ventilation system from debris and drafts. Suitable for commercial, industrial, and residential applications, this accessory enhances airflow control and improves overall ventilation efficiency.