Replacement ceramic disk fits MF10 mini-fogger/mister and other small mini-foggers. Replace disk when fog is reduced or mixed with water droplets. Average life span of a disk is about 1 year if the fogger is used only several hours a day and if the disk is kept clean. Life span is reduced if calcium and algae buildup are not removed. This disk will fit any fogger/mister with the 11mm opening. Actual disk size is 16mm diameter (5/8" approx).