Designed for use with Kaz HealthMist humidifier models 3020, V3100, V3500, V3500N, V3600, V3800, V3850 and V3900, the Kaz WF2 Air Humidifier Wick Filter helps rid the air of harmful pollutants like mold, bacteria, mildew and fungus, while still providing ample humidity in any environment. Each WF2 filter features a honeycomb-style filtration system to effectively eliminate minerals and other pollutants in the humidifier's water. The Kaz filter WF2 ships free from Allergy Be Gone.For use with Vicks humidifier models V3100, V3500, V3600, Kaz model 3020.
For the V3100 you will "flatten" the filter out. If you examine your original filter you will see that it, too, is a round filter.