What do the temperature ratings mean and what is ISO 23537?

ISO 23537 is the common sleeping bag testing standard adopted and strictly enforced by the US since 2017 (Previously known as EN13537), so we decided to test our products according to the toughest standard in existence.  Here is a brief description of the temperature ratings:

Comfort: the temperature at which a standard woman wearing nothing but the Selk'bag can expect to sleep comfortably in a relaxed position.

Limit: the temperature at which a standard man wearing nothing but the Selk'bag can expect to sleep comfortably in a relaxed position. This Temperature is what you will see in all our products and it the most used across the market.

Extreme: the temperature at which a standard woman wearing nothing but the Selk'bag can remain for six hours without risk of hypothermia or death. The performance of the Selk'bag can be greatly enhanced by employing simple and basic methods.