I can second the sunbeam brand. I had to return one to Amazon because only half of it worked. The second one worked perfectly. I lay it out flat on the bed and sleep on top of it. Mine has a timer that goes up to 12hrs.

One thing I will add is that I was born here and I don't really know anybody that uses them. The first time I encountered one was when I stayed in a friend's guest room at the age of 20 and I never saw one again until I bought my own about 2 months ago.

They're a great way to cut down on heating costs. I want to get another one for my couch.