Lennox X2661 Replacement Water Panel by Aprilaire. Fits Models: WB2-17, WB2-17A, WP2-18, WP2-18A, HCWB17, HCWB217, HCWB2-17, HCWP3-18, HCWP318, WP2-18, WP218, HCWB3-17, HCWB317, HCWP2-18, HCWP218. Size: 10x13x1-1/2"