They help get rid of the plantar fasciitis I developed from walking in shoes with less support every day. I used to be in a lot of pain for just a mile or so; After wearing them for about a month I can run up to 4 miles without much discomfort. Note: I also use Green Superfeet and PF Tape - the combination works really well. They are comfortable, surprisingly light but very comfortable where needed. I had an equally great experience with a pair of Quest 4Ds, which I still love, but unfortunately the ruler is about half a size too small for me. For everything else I wear a size 12, but the 4D is a bit small for long-term use. I bought a 12-1/2 LTR - partly because it's one of the only half-size models in the range - and they fit together perfectly and offer plenty of room. Highly recommended!