This Premium CO2 Back-up system for Premium Ultra-Low Temperature Laboratory Freezers is available for those who require additional security for valuable samples. In operation, addition of CO2 is pulsed rather than continuous, ensuring even distribution of the cooling effect while avoiding excessive consumption of coolant. Using CO2, temperature can be maintained between -55°C and 70°C, subject to environmental conditions. Totally independent system utilizes its own temperature probe and battery back-up to provide protection, even during a power outage. For Freezer Type: Premuim ULT Models. Back-Up System Type: CO2. Electrical Requirements: 120 To 230V, 50/60Hz. Eppendorf® #: U9043-0006.