This is on the first page:
3. When that time runs out will the unit be send them back to Hifiman. At our cost or Hifiman's? Once you have completed evaluating the headphone, the participant is responsible for shipping the headphone back to us. You will get an option (a good one ;-) ) to purchase it if you like. People from southern Asia and Russia will ship it back to our factory in China, and everyone else will ship to our US office.