Holmes HAWF2021 Dual Blade Twin Window Fan This Holmes Dual Blade Twin Window Fan provides relief from hot weather. Draws in cool air from the outdoors or exhausts the stale indoor air. Designed to fit virtually all slider and double hung windows. Quiet and efficient operation makes this idea for living room or bedroom use. Versatile design allows for use on a desk or table as well as the option of being mounted to a wall. The fan's extender panels allow for a safe, custom fit. The manually reversible feature lets you control your airflow for intake or exhaust. FAN TYPE BEST USE FOR... Stand Large blade diameter and motorized oscillation helps to deliver powerful airflow in large living areas where there is ample floor space. Table Small footprint allows for use on a table or desk and is ideal for use in bedrooms or other small living areas of the home. Window Designed for use in most double hung and slider windows. Can be used to bring in fresh air from outdoors or to exhaust stale indoor air. Personal Smaller blade size is designed for personal space cooling and is ideal for use in bedrooms, office cubicles, or dorm rooms. Tower Slim space saving tower designs take up less room than stand fans and is ideal for use in living areas where floor space is limited. Power Larger blade diameter and shrouded housing is designed to provide cooling relief in large living areas. High Velocity Durable construction and powerful air velocity makes this ideal for use in the garage of workshop. PRODUCT FEATURES & BENEFITS Easy Installation Fits double-hung, slider, and casement windows. Extender panels included for a safe, custom fit. 2 Speed Settings Set and control your fan speed for optimal air flow and comfort Reversible Air Flow Manually reverse your fan for intake or exhaust Adjustable Screen Screen expands to fit larger windows and slider safe extender panels offer rigid support for vertical orientation.