An ultra low temperature (ULT) freezer is a refrigerator that stores contents at −40 to −86 °C (−40 to −123 °F). An ultra low temperature freezer is commonly referred to as a "minus 80 freezer" or a "negative 80 freezer", referring to the most common temperature standard.ULT freezers usually make use of cascade refrigeration, which consists of two or more vapor compressors using different refrigerants and an inter-stage heat exchanger to cool the freezer over its desired temperature range.Standard freezers are great for storing biochemical reagents and samples that are not stable at warmer temperatures. Found in most labs in the form of refrigerator/freezer combos, they are perfect for a lab with limited space.