plug in heating pad for your back. Like you would find at any pharmacy store. High setting works perfect. Put the device screen facing up on a flat surface. Lay the heat pad on top of it and then weight it down a bit with a book or two. Gets the heat evenly distributed and perfect temperature without risk of overheating any spots Or if you dont feel like buying one of those then this will work- Wet a wash cloth or hand towel with water and loosely wring out just a medium amount so its still heavy but not too drippy Fold till it fits inside 1 gallon bag zipped shut Actually make sure to not fully zip the bags shut till after you microwave it for about a minute. I like to put it inside a thin t-shirt or pillowcase. That will retain the heat just as long as any of the other pads suggested . And it wont smell weird like some of the grain bags do. plug-in heating pad is my fave tho and it never burns you or your delicate electronics Sunbeam Heating Pad for Pain Relief, Standard Size UltraHeat, 3 Heat Settings...