They know that it can sometimes be tough purchasing things sight unseen, so they are making it super easy for you. Buy it, like it, hooray. Buy it, and it doesn't work, no problem. They stand behind their products 110%, and they mean it. If it doesn't fit, isn't the right color, is not print that you expected, whatever the reason, just send it back for an exchange or refund.
They do have a few requirements, just to be fair - They're happy to take back unworn/unwashed item(s) and they cannot be personalized. This means the tags still have to be attached, they can't have stains, and they don't cover washing mishaps, like bleach in the laundry. The only thing they ask is that you pay the return shipping and include a note in the package with your order number stating if you'd like a refund or an exchange. Then, they'll cover everything from there. See, shopping from the comfort of your home can be a win all the way.