Heated mat?
Something like this: 110V, 730W, 5x2ft. Did anybody use it? When you have a grid power and morning temps inside are in mid 50s (12C). Near floor it's a few degrees cooler. Thick duvet keeps me toasty ...
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How about no power? I use these. When they get too damaged, I replace them. I do not wear shoes inside, even during the winter. Our winters get well below freezing and these help a lot with cold floors. LOTS of places sell them not just HF. So if you have a problem with HF, you can still find them. You may find them called "yoga", "nap" or "play" mats. But they are all the same. https://www.harborfreight.com/4-piece-anti-fatigue-foam-mat-set-94635.html
