I got a pair of these and also a pair of Orthaheel wave sandals. I normally wear US 5 1/2 and so bought a size 6 of each. The Wave is a tiny bit big, and the Kinetic Thong is a tiny bit small, so that my heel is resting on the edge of the shoe. I LOVE the Wave. It is attractive, comfortable, and has really helped with my heel pain. I think I'm going to save the Kinetic Thong for emergencies only. The Kinetic Thong is also wider than the Wave.