Additel ADT 878 [ADT878-700-H-220V] Reference Dry Well Calibrator With Insert H, 33°C to 700°C. Additel ADT878 Dry Well Calibrator has three models to choose from, ranging from -40 to 1292°F. The Process Calibrator option adds an external reference input, a two-channel readout for UUT's and a full complement of capabilities to help with everything from measuring temperature sensors, to calibrating thermocouples, self-calibrating the Reference Well and configuring HART transmitters. Each unit comes standard with a large touchscreen display and dual-zone control.