My thanks to reader (Belle) for alerting me to the Exped Synmat HL Winter M (I had overlooked) which weighs 430 grams and has an R-rating of 5.0 at 183 cm long 52 wide (35 cm at the foot) and 9 thick. You do need a 60 gram bag to blow it up, but this also doubles as a pillow. This is an awesome pad. I only need a mat to be 5’6′ long, so I could cut this down to approx 394 grams.This is serious competition for the Thermarest X-Therm that’s for sure! (Same weight, slightly lower R-rating ie 5/5.7, but over 1″ thicker)
It also comes in a wider configuration the SynMat HL Winter MW 65 cm at the chest and 42 at the foot and 545 grams. This would come down to approx 500 grams at 5’6″.