This is the u-shaped component which encases the Water Panel Evaporator. Their purpose is to direct any mineral which builds up back into the evaporative panel. They prevent water from leaving the evaporative section and entering another portion of the humidifier. Fits models: 560, 560A, 568, 700, 700A, 700M,760, 760A, 768. Also fits Lennox Models: WP2-17, WP217, WP2-18, WP218, WB2-17, WB217.