ALDA diffusers are made of aluminium anodised in natural colour or powder-coated in RAL 9010 white. They can also be coated in another RAL colour on request. SDA diffusers are made of steel and powder-coated in RAL 9010 white. Other RAL colours and stainless steel versions are available on request (SDA-4 only). ALDA and SDA ceiling diffusers are available with blades adjusted to 1-, 2-, 3-, or 4-directional flows.