Commercial and Industrial Disposable Panels are economical air filters designed for light-to medium duty air filtration applications and are constructed for high performance and durability. Fiberglass Media (Blue) Constructed with high grade progressively dense glass fibers. The air entry side is composed of open coarse fibers, while the air exit side is made up of tighter fibers. This dual density media configuration allows for proper depth loading and full utilization of the filter media. Each fiber is coated with a non-migrating adhesive to enhance filter performance. Sturdy One-Piece Frame. Utilizes a one-piece moisture-resistant craft board frame for strength and ease of installation. The interlocking miter corner provides extra strength and durability. No extra metal support is needed making the filter more environmentally friendly. Specialized Sealant. A thermoplastic sealant is used to bond the filter media to the frame on both the upstream and downstream sides of the filter. This bond eliminates any air bypass and helps provide rigidity to the filter. MERV 4.