One size fits all. This pear shaped compression board the best addition to your waist training garment. The CQ corsets are not steel bonded so they have flexi bonds that keeps shape as long us your in a upright position, but what happens when your sit or your bend, The flexi bonding bends with you which is good so the wires aren't cutting into your skin but what happens when you wear your corset and SIT for a long period of time??? It forms a pocket The compression board keeps the corset in the straight up right position also pulling in the lower abdominals.