Must keep feet flat and in center, which causes fatigue of your leg muscles.
The heating element(s) seem to be only in the center 10-12 inches of the mat. There are 4 to 5 inches on both sides that are not heated. Not much heat is radiated and reflected from the insulated cover. The temperature goes in increments of 80, 90, 100, 110, 120, 130, 140, and 150. I'm not sure how accurate those temperatures are, or if they are steady. The mat does heat up quickly. You must keep your knees close together and your feet flat in the center of the mat to feel the heat, and the heat is only on the soles of your feet. When I relaxed my legs while sitting, then only the outside of my feet were in contact with the heated mat. The tops of my feet/toes did not feel the heat much. After a while, my legs became fatigued.
Rating: 3 stars