The outer fabric looks like denim, but it's very soft and stretchy. The inside is brushed for warmth. These are extremely warm, brushed-fleece long pants, perfect for the cold season. The fabric stretches, but it seems to be designed for those with a slim build. I've worn them 2 or 3 times, but I outgrew them too quickly. There are no noticeable stains or dirt. Please purchase if you understand that this is a used item. There may be some fold creases from being stored at home, so please be aware of that.