WTS Foot Warming heat pack, self adhesive, $1.80 per pair, I have 4 pairs. 90mm x 70mm. Keeps warm for 5 hours.
WTS Body Warming heat pack, self adhesive, $2.80 per pack, I have 10 packs. 130mm x 95mm. Keeps warm for 12 hours.
Very effective, just came back from winter vacation watching northern...