*from their website* Description Horizontal or Vertical Installation 3 Comfort Settings Reversible Airflow Adjustable Thermostat Bring in the Breeze Blow fresh air into your home or expel air to the outdoors for cooling cross-ventilation with the Holmes slim window fan. Designed with 3 independently controlled fans, it features manual controls and a thermostat to ensure ease of use. You can install this fan vertically or horizontally with the extender screen locking the unit in place. The slim design allows you to utilize window space without obstructing your view. 3 independently controlled comfort settings for each fan Adjustable thermostat Manually reversible airflow Designed for use either horizontally or vertically Firm Fit locking extender screen