The most used temperature for calibration is 0°C. 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.