MERV8 PracticalPleat™ Filters are high performance filters designed to replace standard 1" filters. The Practical Pleat's patented gasket conforms to imperfections in the filter track, eliminating air bypass and preserving the integrity of the MERV8 Rating. This unique gasket fits into the one-inch filter slot with the excessive depth of the filter protruding in the duct system or return plenum. Custom Sizes also available , if you cannot find your size , Contact Us. MERV8 Practical Pleat filters can last up to 4-months.