The internal volume for this Telstar -45ºC portable stirling freezer is 25 liter. Our portables require only 12 Volts input and use less than 150 Watts of power. In fact, the Telstar portable can be powered by a standard 'cigarette lighter' port in a car or by a UPS power supply. We are a pioneer in the market using standard only natural refrigerants in our portable freezers. Moreover Telstar portable freezers offer definitely the lower power consumption and noise level.