These unique devices are the only ones that provide thermally-efficient ventilation for a home while simultaneously filtering incoming air to increase freshness. Their patented Air-to-Air Heat Exchanger technology helps create a more comfortable indoor environment while augmenting air quality. Eliminating the need for ozone generators or ionizers, which artificially reproduce the negative ion content of fresh air, these units circulate natural, fresh air into a home from outside. At the same time, they shunt stale internal air and control indoor humidity. Normally, an open window accomplishes the same task, but at a loss of heat that results in uncomfortable drafts during colder months. These devices transfer at least 90% of the thermal energy from the outgoing air to the incoming fresh air, helping prevent significant temperature fluctuations indoors. The filtration unit in the heat exchanger traps 85% of incoming particles as small as 5 microns (a human hair averages between 70 and 100 microns in width). The random matrix polyester-heat exchanger may be easily removed for washing. Both models use a new ultra-quiet, high-efficiency variable-speed motor. All components are heavy steel with corrosion protection from impact-resistant plastics, and exteriors are painted in scratch-resistant electro-plated paint. Both units are ETL rated to UL standards. Window Unit. Ideal for use in single rooms up to 1,500 square feet, this model mounts in a double-hung window or wall just like an air conditioning unit. Plugs into AC via an 8-foot cord. Off-white. 12 7/10" H x 22 1/5" W x 23 1/2" L. (55 lbs.)