ca2421-s triangle fan’s direct drive whole house fans are an efficient, economical way to cool your home. Fans will cool your home to the outside temperature 5 to 10 times faster than central air conditioning at less than 1/10th the cost!! features two speed direct drive motor. two speed pull chain switch included. three wing propeller. rubber mounts for quieter operation. heavy gauge steel construction. easy installation. css no cut joist shutter included. optional 12-hour timer available (sold separately).