R-value: putting a number on warmth
When buying a sleeping mat, most people shop around a bit and compare the different brands and models available. Important points such as price, quality, comfort, ease of use, reliability, compressibility and warmth all enter into the equation. But it's that last one, warmth, that's a bit sticky. With all the other parameters it's pretty straightforward to compare mats. Price and quality go together and info about comfort, ease of use, reliability, and compressibility can all be culled from online reviews, in-store poking and prodding, and manufacturer websites. But this warmth rating, R-value, isn't as easy to accurately verify across brands and deserves an explanation, so we thought we'd clarify a few points.