REI doesn't list the material specs correctly - this is the actual specs and a good description:
"the grey side (bottom) is a higher-denier fabric (70 denier nylon with soft grip) that helps keep the pad in place on the floor of your tent -- no backsliding. The top is a finer, 30 denier High Tenacity Nylon, which also helps keep your sleeping bag from scooting around while you doze".
I have this XTherm pad, and A.) it feels very sturdy, no worries at all even with my dog and her big nails B.) the warmth is unreal, I truly feel I'll be able to use a bag with a higher temp rating than before this pad, probably by a good 10 degrees.
I still like a non-tapered pad for floor less shelters or snow camp as I like my bag to float on a pad the whole night and not have it fall onto snow or dirt. But for all other uses, 3 seasons plus well into shoulder seasons this pad will be a great new companion.
Have to love the Made in USA aspect as well!