I told you your better with a keyboard, I actually put the zrest under the pad, I stayed warm on my last trip, it was 17 degrees and I was in a 3 season tent with a 20 degree montbell bag, BA insulated air mattress and the centraly located zrest, and the ground was very much frozen. My next trip should be even colder which will be an even better test, and I was wearing long johns, synthetic bottoms and wool top.