Contains an Antimicrobial Treatment by MicroFree to prevent growth and migration of mold, fungus, algae, and bacteria. Also features durable construction for maximum life and humidity output. Replace your filter every 4-6 weeks for best performance and comfort Fits Humidifier Models: HD500, HD-500, HD1205, HD-1205, HD1211, HD-1211, HD2412, HD-2412, HD6200, HD-6200, HD7002, HD-7002, HD7005, HD-7005, HD12110, HD-12110, HD12111, HD-12111, HD17020, HD-17020, HD17021, HD-17021, HD24120, HD-24120 Emerson Replacement Humidifier Part Numbers: HDC2, HDC-2, HDC2R, HDC-2R, HDC411, HDC-411, 290w. Note: HD1211, HD-1211 AND HD2412, HD-2412 RPS BestAir Replacement Part Numbers: E2R Approx. Measurements: 6-3/8" L X 2-3/8" W X 11-7/8" H Please Note: These Filters are Replacements Manufactured by Best Air RPS Products. Fit and Function are Backed With a 30-day Money Back Guarantee.