The OdorGuard(r) ring panel air filter fromD-Mark, Inc. (Chesterfield, MI) contains granular-activated carbon to remove odors and gaseous and particulate pollutants. Types ranging from light to heavy-duty odor removal are available. Ring panels are available with granular carbon loadings of 45, 300, or 345 grams/sq ft, and the filters have internal wire support rings and are self sealing in front, rear, and side access systems.