These air conditioning pan treatment tablets are an EPA-registered biocide to prevent blockage in AC and refrigeration drain lines from buildup of bacterial slime, rust, scale, air-borne dust, silt and solids. Once in a drain pan, its unique dispenser stops water overflow for up to 3 months. Actabs JR. tablets are packed in bulk for economic monthly treatments for all systems, including commercial size A/C units commonly found in motels, hotels, hospitals, nursing homes, schools, apartment and office buildings.