This is an extra-wide (10 inch) ab belt, designed to encircle your waist and cause sweating of your mid section, busting belly fat. It is designed to be worn directly against the skin, though I find it more comfortable worn directly over a t-shirt. It can also be used a a girdle to hold your belly in. It does not ride up or down, but stays in place when put on properly. I bought an XL size, assuming it would match shirt sizes. I was wrong, the belt I got wraps 1.5 times around my body, which is fine but a bit of an overkill. Be sure to check sizes and measure your belly before ordering. The best AB belt I have ever seen. It will be used often.