The 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 (except closed case styles). Available in three case styles; closed metal, open metal, or closed plastic. All Enviro-Safe glass thermometers contain an environmentally friendly non-mercury liquid that is 100% certified as non-toxic, non-hazardous, and fully biodegradable. In case of breakage the liquid can be cleaned up easily with soap and water. Each thermometer features a green liquid and white back glass. These thermometers also feature recyclable packaging, RoHS compliant and have a statement of accuracy.