The soles are extremely flexible, and they appear to be a one-piece, molded, comfortably soft rubber. I am a paraplegic and have terrible problems with my feet swelling and my shoes getting too tight, but with these, I just readjust the size and they always fit perfectly. This did not fit my size 52 cm 2017 Salsa Vaya. I just placed my 3rd order for these earphones. The first pair is a two strap toe loop one, it took me so many months to break into them after daily wear. The Currie version is made by the same folks. I bought these that I am doing a review for and I like the stem better, NOT MADE OF WOOD, BUT the spiral swab is not tight enough, cotton frays and if you wet them the spiral just seems to disappear and flatten out. 5M, I recommend 7M I really like the look and feel. These are so cute and very comfortable.