The Perfect 16 "whole-house" air purification system is a premium, Swiss-engineered, "medical-grade" HEPA-TYPE, MERV 16, extended-surface-area filtration system. (170 sq/ft and 210 sq/ft; 3 ton & 5 ton, respectively.) It filters 100% of the air from your fresh/cold air side and 100% of your cirulatory air in your home through the cold air returns. In fact, at it's maximum capacity of 2000 CFM, you could get 125 completely purified air exchanges in your home, per day! The Perfect 16 has the lowest pressure drop and the highest retension rates for particles anywhere between 0.3 microns (95%) and 0.003 microns (85%,) inclusive. Filters last an amazing average of three years and the cost to replace them is very competitive within the HVAC market! It gathers all particulate (dust, pollen, mold spores, pet dander,) down to the virus and bacteria level and it will even remove smoke or vehicle emission particulate. It is the best and only way to protect your home from constant pressures of outdoor pollution. Whether you live next to the heavily conjested trafffic of city roads or on the quietest country gravel road, you too can benefit from the amazing 90% reduction of dust in your home. We guarantee it and we test and confirm it, before we leave your home!