The EFFC is return air valve for installation on ceiling or wall. The air valve has a lockable central cone which is rotated to adjust the pressure and consequently the air volume. The EFFC is manufactured from sheet steel and is powder-coated to white RAL-9010. Available in the following connection diameters: 80, 100, 125, 150, 160 and 200. It is recommended to use EFFC air valve in extract air applications. If used in supply air application, the pressure losses and sound level will be much higher than anticipated and the selection diagrams given, will no longer be valid.