A dispenser includes a base holding a cartridge that includes a volatile material reservoir. The base includes a plurality of ribs that support a peripheral flange of the cartridge. The plurality of ribs support a portion of the peripheral flange having a permeable membrane disposed thereon. A first removable cover is attached to the base and has at least one aperture and a first regulating plate. The first cover may be removed and replaced by at least a second cover that has at least one aperture and a second, different regulating plate.