These maximum strength mouse away solids are NOT intended to be used in areas that people live in on a regular basis. We recommend them for attics, basements, garages, in stored vehicles and outdoor spaces. We do not recommend them in areas that people frequent. The difference between the regular Mouse Away Solids and the "Max Strength" is the addition of menthol crystals. Menthol Crystals concentrate the aroma and evaporate more slowly.