These heel wedges are to help correct Pronation/Supination of the foot. See diagrams for explanation. I have slight supination in my right foot from an injury and will only be using the lowest angle wedge. I'm not medically trained so cannot recommend using these wedges especially if you have pronounced pronation/supination. Use at your own risk!I suggest gluing these to the bottom of a soft insole before putting in your shoe. If your shoe is contoured you can mold the insert into the shape of your shoe by warming it first. I have added three different sizes: small 37EU, 4UK, 4 1/2US medium 42EU, 7 1/2UK, 8US large 46EU, 11 1/2UK, 12US The sizes aren't exact. I've also done 4 different degrees of angle 2,3,6 and 9. All the files are called supination but the design is symetrical so if you have pronation in your right foot just use the left foot supination file.