Togs and R Values: Typically used in the British textile industry, one Tog corresponds to the heat insulation capability of clothing etc which maintains a temperature difference of 0.1°Kelvin while passing a heat flux of 1 Watt/m2*. Some manufacturers (mainly US ones) give an R Value for the insulation properties of their mats. By this they mean an imperial equivalent (°F-ft2-h/Btu). To convert Imperial R values to Togs, multiply by 1.76228. To confuse matters there is also a metric R value, more properly called an RSI value (10 Togs = 1 RSI).
The higher the Tog or R (or RSI) value the better the insulation provided.
If you aren't totally confused by the above you should add to the mix that testing for R/Tog/RSI ratings is not by any means an exact science and that it is also expensive so, it is alleged, some figures that are given may be acquired by doing little more than taking a competitor's figure and adding a pinch for good measure. Of course, who is alleging what about whom is also not easy to ascertain!
*NB One Tog was originally a war time measurement of the amount of warmth retained by a typical male wearing a three piece suit - it originated from research done in the North of England - hence the term tog (though this in turn is thought to originate from the Roman word toga)!