The Filtrete 18x18x1 AC Furnace Air Filter is a high-quality filter designed for furnace applications. With a MERV 11 rating and MPR 1000 technology, this filter is effective in removing dust and other airborne particles. It has an electrostatic filtration technology that captures airborne particles as small as 0.3 microns. The filter comes in a convenient 4-pack, making it easy to ensure clean and healthy air in your home for an extended period of time, with a filter life of 3 months. Made by Filtrete, a trusted brand in indoor air quality, this filter is a reliable choice for keeping your home comfortable and clean.