This adjustable plastic vent is designed for openings up to 229mm x 229mm (9" x 9") and provides an airflow of 15,500 sq. mm when open. The integral flyscreen keeps out insects and spiders, making it suitable for most domestic applications including larders and cupboards. This plastic louvre vent is ideal for providing air flow through a building, helping to reduce problems caused by stale air, dampness, smells and condensation.