Yes, it is filled with some type of foam that provides insulation. It's over 2 inches thick and almost 3 in the head section. Based on my past experience with Thermarest pads of lesser thickness ...... you could use this on snow and be comfortable. It was in the high 30's in Yosemite a few weeks ago and it was quite comfortable with no cold sensation. I don't know the exact make up of the foam or how to calculate the R Value of a particular insulated pad.