OOFOS OOriginal Thong :: Looking for the perfect post-run footwear? Oh my! The OOFOS OOriginal Thong is just the thing to make your feet say "oooh!"". Like a foot massage in every step your feet will feel relaxed and rejuvenated with the unique arch support built into this slip-on style. Less pain more gain every time you wear your new favorite sandals! Unisex sizing is in men's D width. Women size down 2 sizes. Ex.: If you are a women's size 7 in your running shoe you will choose unisex size 5