This fits your .

These Holmesreg; aftermarket humidifier wick replacement filters fit Holmesreg; model HM5100, HM1800, HM1840, HM1845, HM1850, HM1851, HM1855, HM1865, HM1888, HM1889, HM1895, HM1975, HM2059, HM2060W, HM2090, HM3000, HM3800, HM3850, HM7600, and HM4000. [HM3000 and HM4000 require 2 filters. HM3800 and HM3850 require 3 filters.] They measure approximately 7 1/2 H x 5 1/4 ID x 7 1/4 OD x 1 Thick. Features an antimicrobial agent! Honeycomb filtration to trap mineral pollutants found in water and help prevent them from entering your home. For optimum performance, replace filter at the beginning of each season or every 2 months depending on use. This is an aftermarket filter.

pasutech Holmes HWF65 Humidifier Filter (Aftermarket) - B00CX98X8C