The Isotech Model 875 Ayres Calibration Bath consists of a container of aluminum oxide powder with a porous base plate. Sufficient air is passed through the base plate to motivate the powder into a fluid like state so that it will flow, display buoyancy effects and have good heat transfer characteristics. The 875 features a temperature range of 122 to 1292°F (50 to 700°C) and a volume of 67mm diameter, 475mm deep.

The bath is suitable for comparison calibration or use with fixed points. It offers exceptional stability: ±0.005°C at 150°C, ±0.005°C at 450°C, and ±0.020°C at 660°C. Serial interface, PC cable and software are included for automated operation and data logging.