Replacement Vornado HU1-0006-11 Humidifier Filter - Quantity, 5 Replaces Vornado MD1-0002, MD1-0001 Air Filter Traps Liquid Impurities & Dissolved Solids Before They Become Airborne For best results, change air filter at least once per season or more often depending on air quality and use. Essential for Allergy Sufferers.
