The Systemair Revolution Silenced EC fan range has been improved to make this V2 version the best yet. The Revolution Silenced EC fans are available in a variety of sizes: Revolution Silenced 150 EC V2: Max Airflow: 764m‚³/h Revolution Silenced 200 EC V2: Max Airflow: 1345m‚³/h Revolution Silenced 250 EC V2: Max Airflow: 1787m‚³/h Revolution Silenced 250L EC V2: Max Airflow: 2102m‚³/h Revolution Silenced 315LP EC V2: Max Airflow: 2224m‚³/h Frictionless EC motors are the most efficient, quietest, and cheapest to run option on the market. Whilst still moving massive amounts of air. Cheap to run - savings of up to 50% versus traditional AC technology. Super quiet due to the frictionless EC motors Immense Airflows. Easy installation. EC fans cannot be operated without an appropriate EC fan controller. We have a number to choose from to best suit your needs.