Uses up to 50% less water. Anti-Microbial helps protect filter from the growth and Migration of Mold, Fungus, Algae & Bacteria. For Best Performance, change at least twice per heating season, maybe more depending on water conditions & frequency of use. Waterpad that fits: Aprilaire 110, 220, 550, 550A, 558 (10); Bryant HUMBBSBP 2212, 2312, 2412, HUMBASBP 2312, 2412; Carrier HUMCCSBP 2212, 2312, 2412, HUMBASBP 2312, 2412; Chippewa 220; Hamilton 12HF (EP037); Honeywell HE220A/B, HE225A/B; Lasko 5000L, 5000EC, 6000; Lennox WB2-12, WB2-12A; Totaline P110 SBP 2212, 2312, 2412. Color: Whites.