Manufactured to order from 0.8mm or 1.0mm galvanised mild steel depending on size. Grille boxes are available with or without a 20mm flange at the open end.

Circular Plenums fit the neck of Swirl Diffusers and do not require a flange as standard.

The locating screw that comes with the Swirl Diffuser fixes to the locating bar inside the plenum.

Internal equalising perforated plate and brackets are available as an optional extra.