ASTM 128F Brookfield Viscosity Thermometer, 29.5 to 34.5°F, Mercury Fill. These liquid-filled glass thermometers are manufactured to very rigid specifications and are guaranteed to meet accuracy requirements set forth by ASTM. The suffix portion of the catalog number is the ASTM designation for that particular thermometer. Factory calibration certificates are available for an additional charge. Please specify calibration points at the time of order.