Filled with an environmentally safe liquid and dye which eliminate the hazards of mercury in case of breakage. Each thermometer is individually serialized and a certificate is supplied to its accuracy. The thermometers are permanently marked and have a blue liquid against a white background for easy reading. • Non-toxic liquid. • Blue liquid, white background for easy reading. • Certificate of Accuracy included with each thermometer. • Permanent scales. • Several ranges and divisions to choose from.