This 4 inch tall La Crosse Technology Capillary Window Thermometer is a mercury-free design. It has versatile mounting using the provided suction cups or nails either front or back. This window thermometer is also suited for indoor or outdoor use for versatility. Window thermometer measures temperature (F and C) Mounts indoors or outdoors for versatile use Hang on a nail or with included suction cups Capillary thermometer is mercury-free and weatherproof Measures 4.4 H x 1.5 W in.