The Direct Air right angle high efficiency air filter is designed for space saving vertical installation. Removes house dust, insecticide dust, moths, pollen, mold spores, bacteria, dander, cooking smoke and grease, tobacco smoke, fine particles and more down to 0.3 microns (1/84,000 of an inch). Space-saving design that recovers 6 to 8 inches in vertical installations. No need for a 90° duct adapter, as it acts like a wing and distributes air evenly over the entire filter surface.