Keep humidifiers clean and scale free with Humidi-Pro. Inhibits scale for one season. Install on the water line that supplies water directly to the humidifier. Equipped with compression fittings for easy installation and seasonal change-outs. Clean pad or install new pad before installing Humidi-Pro. For best results humidifier should have a daily dump of water from the sump to diminish scale forming minerals. Install a new Humidi-Pro before each heating season. Operating temperature, min./ max, 40 - 80 F