Before revision: Devices typically comprises a series of parallel plates of aluminium, plastic, stainless steel, or synthetic fiber, alternate pairs of which are enclosed on two sides to form twin sets of ducts at right angles to each other, and which contain the supply and extract air streams.
After revision: copperDevices typically comprises a series of parallel plates of aluminium, plastic, stainless steel, or synthetic fiber, alternate pairs of which are enclosed on two sides to form twin sets of ducts at right angles to each other, and which contain the supply and extract air streams.