Installed above a customer entryway, these commercial air doors, or "air curtains" will keep warm air inside and cold air outside. Air Doors work by creating a laminar air-flow separating two different air zones. - - The commercial models are well suited for businesses where doors are left open or are in continuous use. Recommended for doors up to 7' high, their low profile allows them to fit above doors that have a relatively low ceiling height. These models are among the quietest in the industry. Voltage must be specified upon ordering, electrical specifications available by calling. - - Recommended options: - Door micro switch (automatic on/off control) - - Features Include: - Widths from 36" to 72" available - Whisper quiet operation - Variable speed motor and switch - 7-1/2" low profile design perfect for restricted ceiling height - Specially formulated poly housing