The normal way of creating 0°C is via a mixture of ice and water in a Dewar Flask.

However, this can give errors of up to 4°C because water is densest at 4°C and so as the ice melts the temperatures at the bottom of the flask can rise to 4°C.

In the design of the ice flask offered by Isothermal Technology Ltd., these problems have been eliminated by stirring the water/ice mixture and segregating the ice from the water in the measuring zone.
This stirred ice/water bath is designed and built according to National Laboratory recommendations.

Using demineralised water, accuracies of ±0.005K are obtainable. Typically the bath will last for 4 hours before recharging with ice.

The ice is contained around and below the compartment where up to 4 probes can be placed for calibration or referencing purposes.

An option permits a water triple point cell to be maintained within the stirred ice bath.