I read the good and bad reviews and took my chances. I let it run for 45 minutes on a drive to town on a 20 degree day, not even cold. It does not get much warmer than just a plain blanket, unless you wrap it around your hands and double or triple it. Flat across the lap there was no warmth at all. I could feel a little heat if I squeezed the blanket between my fingers right over a wire, and then just barely. The blanket is constructed with 2 sheets of polar fleece and the wires are just loose between them, no quilting or any means to keep the wires in any particular place, like a big pocket. With no real contact the heat is as likely to just go out the top as it is to warm you (if there was any). I ended up sending it back. It was to be an extra heat source for a commuter car in the winter for emergencies (above and beyond the sleeping bags already in there) and over a little dog kennel in the car when we had to leave her in the car. The dog would freeze with this thing.