These high precision liquid-in-glass mercury thermometers are hand blown, which bear graduations, numbers and letters etched into the glass and filled with and inert gas above the mercury column

ASTM thermometers are used for a variety of specified tests which quantify and qualify repeatable test results in the fields of oil & petroleum testing.
WARNING—Mercury has been designated by EPA and many state agencies as a hazardous material that can cause central nervous system, kidney and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury containing products. See the applicable product Safety Data Sheet (SDS) for details.

These thermometers were designed for specific testing and can be calibrated to your specific requirements.