Nontoxic, biodegradable liquid- and dye-filled Eliminates the hazards of mercury during disposal or in case of breakage Safety-Coated Thermometers contain liquid and glass inside the Flouro-Polymer coating-protects against breakage, keeps contents safe. Serialized Thermometers contain a blue liquid against a white background for easy temperature reading. Certificate of accuracy included with each Thermometer. Uncoated Pocket-Style Thermometers also available. Pocket-Style Thermometers are 6"L.