Tips For Daily Use - For best results, flip your compatible for humidifier T filter daily and only fill humidifier tank with distilled water (this applies to all of filters). Hard water degrades ALL compatible for humidifier filters and yellows them prematurely Upgraded Blue Pre-Filter Layer - Our premium upgraded blue layer pre-filter helps reduce the quantity of large particles circulating in your air Compatible With for Humidifier Filters Replacement Filters - Compatible with HTF600 Filter & Filter T. designed and manufactured for humidifier models HEV615 & HEV620 Value Pack - Premium replacement for HFT600 Filter T filters for your HEV615 & HEV620 humidifiers. Made from high-quality, material with an upgraded filter design to both filter large particles and maximize moisture output Installation Instructions - Soak your replacement wick for T Filter for humidifier HEV615 and HEV620 in cool water before replacing to uninterrupted moisture output. Place in filter housing with blue layer facing outwards (towards you)