COOL YOUR HOME WITH FRESH AIR. The Holmes Digital Window Fan has dual blade operation with two speed settings and a programmable thermostat that let you maintain a set temperature and keep air flow at a comfortable level in medium-sized rooms. The dual blade fan is designed to fit most double-hung and slider windows and includes an expandable side panel with extender screen for a customized and secure fit. Designed to keep a cool breeze in your office, bedroom or any room you wish.