The sleeping bag test results provide information about the temperature range in which a sleeping bag is suitable for use. The ISO 23537-1:2022 standard provides a method for determining three temperature ratings: Comfort Temperature, Limit Temperature, and Extreme Temperature.
Comfort Temperature is the temperature at which a standard woman (25 years old, 60 kg, and 160 cm) can sleep comfortably in a relaxed position inside the sleeping bag. The comfort temperature is determined by the average person's thermal comfort, and it's measured in degrees Celsius.
Limit Temperature is the temperature at which a standard man (25 years old, 70 kg, and 173 cm) can sleep for eight hours in a curled-up position inside the sleeping bag without feeling cold. The limit temperature is an indication of the lowest temperature at which the sleeping bag provides sufficient warmth to protect against hypothermia.
Extreme Temperature is the temperature at which a standard woman can remain for six hours without risk of death from hypothermia. This temperature is only intended as a survival rating and not a comfort rating.
It's important to note that the temperature ratings provided by ISO 23537-1:2022 are based on standardized test methods, and individual comfort levels can vary depending on factors such as metabolism, age, and overall health.
Overall, the FIELDTEST T-Rex sleeping bag has been certified to provide comfortable and safe sleeping conditions in temperatures ranging from -4°C to -11°C, with a survival rating of -30°C.