Double-safe thermometers are PFA safety coated In the event of breakage the coating will help contain the broken liquid and glass. Each thermometer features a black liquid and yellow back glass which creates a distinct contrast making this thermometer very easy to read. 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, ring top anti-roll fitting, individual serial numbered and have a statement of accuracy.