This Nuaire NU-5500 DH AutoFlow CO2 Air-Jacketed Incubator is in used condition, has been tested and is guaranteed to be fully functional. This unit came from a local lab that had surplus equipment and shows some aesthetic signs of use. As seen in photos 2 and 3, unit was successfully tested to a setpoint of 37 C. We urge customers to view all photos as they show overall condition, included accessories and functionality. We will be happy to provide additional information as well as photos so please feel free to contact us with any questions. Please note: There is a motor fan missing as seen in last photo. We will attempt to replace prior to shipping. Also, another small issue worth noting is the incubator is slightly noisy when running. These issues do not affect functionality but have been reflected in the list price. NU-5500 The NuAire DH AutoFlow Incubator uses a microprocessor based, non-dispersive infrared CO2 sensor. The amount of energy diffused to the detector is an exact logarithmic function of the CO2 concentration in the gas between source and detector. The wavelengths used are absorbed by a filter in the CO2 bandwidth making the measurements insensitive to other components, such as water vapor. Advanced design provides a very stable drift-free output requiring less frequent calibration. The sensor is within the chamber air plenum so very accurate CO2 control is achieved. A HEPA filter surrounds the blower on the positive pressure side and continuously cleans the circulated chamber air within the incubator. The HEPA filter uniformly distributes and cleans the air within the chamber at a rate of one complete change per minute.