Bought these to use as liners for my crocs (apparently crocs won't sell you replacement liners so you need at least a small sock otherwise the liner that comes with the crocs gets yucky fast). I bought these quickly, then glanced at reviews when the product arrived and I didn't see any washing instructions. Some people love them, others had complaints, but I found that for me they fit perfectly (I ordered directly based on my shoe size), are super comfy and breathe, and even though I washed them (in cool water) before wearing and dried them on low heat, the rubber band around the edge kept them staying up. The ones I got are thin but not overly so (as some reviewers mentioned) and the fabric is sturdy although soft. If this product sounds like it might fit your needs I definitely recommend trying them. I'm still not sure what the washing instructions are supposed to be but cool wash low dry is working well for me.