DESC: The GuardianPlus Air Systems represent a revolutionary line of whole house HEPA filtration products featuring patent pending technologies and manufacturing processes. HEPA (High Efficiency Particulate Air) filters are among the most effective available. They capture 99.97% of all particles as small as 0.3 microns. They help reduce allergy symptoms, asthma, reclining colds and cough. Proper ventilation is vital for healthy indoor air. Ventilation models exhausts harmful pollutants that are not eliminated by filtration, such as carbon monoxide and other harmful gasses to The outside. And it controls excess humidity, especially important during cold seasons. GuardianPlus Air Systems are the only whole-house filtration devices on the market to feature an electronic, low voltage wall mounted control switch for convenient operating flexibility.