Slant/Fin Replacement Mineral Absorption Pads for SF211 and UV Bulb Set of 6 replacement mineral pads and 1 UV bulb for Enviracaire/Slant Fin Humidifiers: 211D series Pads will generally last 2-4 weeks depending on hardness of water. Fits Slant Fin GF-211D and Enviracaire EWM-211D Ultraviolet light puts an end to bacteria that may breed in standing water