The AA300 air curtain protects your operation & makes staff more comfortable when the window is open. In SUMMER mode, it satisfies health department codes for a fly fan, deflecting insects, car fumes, and dust. In WINTER mode, the AA300 provides radiant heat for your operator. Air flows on the outside of the window so the sound does not interfere with customer or staff communication. This also helps reduce HVAC air conditioning & heat loss. It can be mounted above any flush-mount window.