Free heat from your clothes dryer. Just flip a lever on the Deflect-o and this heat goes into your house instead of up the vent. An operating clothes dryer produces enough hot humidified air to keep a 30' x 24' room warm (20,000 BTU’s per hour). Easy to clean screen stops lint but lets the heat and humidity go through. Easy to install in just a few minutes. Also good as year-round lint trap where outside venting not practical.