These thermometers are ideal for use in laboratory, biology, chemistry, university, photographic, food/beverage, petrochemical, automotive, wastewater and many other general purpose applications. The protective plastic case protects these thermometers from accidental breakage during use and storage. The section of the case that surrounds the bulb has small openings for circulation. All DURAC Plus® thermometers feature markings that are permanently printed on the glass, blue spirit liquid that has a dark scale contrasts against a white background.