They aren't effective at trapping the small particles that harbor bacteria, pollen, mold, dust mites and other irritants. If someone in your family is prone to respiratory ailments or allergies, you might want to consider a higher-performance filter.
Price includes a year's supply of refill pads.
However, most filters share basic features. They're made so airflow through the filter creates a slight electrostatic charge that attracts and holds airborne particles. Most also contain an antimicrobial additive to help control mold, mildew and bacteria. Some filters also offer an optional activated-charcoal screen, which helps with odors and cigarette smoke. Most high-performance filters are washable, and with proper care they can be used for up to 10 years.