normally has profiled blades to direct the air at an angle as it leaves the unit into the space . Alternately ,Grille is used for vertical discharge

-they are fabricated of aluminum,  stainless steel ,plastic painted or chromated.

they come in different shapes like bar,egg,linear,louver depending on its application.

TYPES OF DIFFUSERS/GRILL

Lover Bladed Diffuser

these are used to supply air at ceiling level. The curved blades deflect air in one, two, three or four directions depending on where the diffuser is situated.

Linear Slot Diffusers

These are used for an alternative air distribution pattern and for aesthetic reasons.

Air can be delivered around the perimeter of a room as opposed to point sources interposed in a ceiling space.

Linear slots can be used for return air as well as supply.