Replacement 1099-20 Evaporator Pad (2 Pack). The aluminum evaporator material is enclosed in heavy wire frame and channeling. Also has a super absorbent coating for maximum water distribution and increased humidity output. This item must be replaced at least once per year for optimal performance. Fits Model 1099, 1099L, 1099LH, 1099R. GeneralAire® Vapor Pad, For Use With: GeneralAire® Humidifier Model 1137, SL16, 1099LHS, 1040, 1042, 709 and 1137, Trion G100, G300 and Herrmidifier 100, Protech 84-25054-01 and 84-25054-05, Aluminum, 1-1/2 x 14-1/4 x 12 in