Quantity of (2) : New Vornado Replacement Humidifier Mineral Cartridges, Filters Out Minerals That Help Form The Residue Build Up Known As White Dust, Contains A Special Blend Of Water Softening Minerals That Reduce Lime & Calcium Build Up, Completely Odorless & Extends The Life Of Your Humidifier, For Use With Vornado Ultra3 Ultrasonic Humidifier model HU1-0031-06