Air Quality Improvement: Activated carbon helps reduce household odors such as cooking, cleaning and pet odors Maintenance: Recommended to change every three (3) months, or more often in harsh environments, for maximum efficiency Approximate Dimensions: 16 1/4 x 11 3/4 x 1/8 inches What You Get: Four (4) Pre-Filters Filter-Monster branded carbon pre-filter replacement for compatible with Whirlpool AP25030K, APR25130L, APR25530, AP150, AP250 pre-filters.