An R-value is a standardised, globally recognised measure. It's officially known as the ASTM FF3340-18 R-value standard.

It is used to indicate how well your sleeping mat will stop heat loss. It’s a scientific measurement that is more accurate than a suggested temperature rating generally given by some companies.

The R-value is a measurement of thermal resistance that indicates a material’s ability to insulate. In real terms, the R-value tells you how well your sleeping mat will help to keep you warm as part of your sleep system.

All OZTENT mattresses are tested to this standard to help you make the right decision when choosing a mat.