This rugged Enviro-Safe® brand, NIST-certified lab and field thermometer does not contain mercury, mineral spirits, or alcohols, but rather a biodegradable, safe green dye, should breakage occur—less likely since it comes in a protective casing! The 6" long thermometer can be removed from the case for direct readings. Attach a string or cord to the top loop for immersion in water. This precision thermometer meets GLOBE specifications. Please note: All thermometers should be stored at a slight angle (base down) to prevent separation.