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: 19 1/8 x 16 1/2 x 1/8 inches What You Get: Four (4) Pre-Filters Filter-Monster branded carbon pre-filter replacement for compatible with Whirlpool AP51030K, AP45030K, APR45130L, and WP500 Pre-Filter helps reduce odors and maximize filter life.