Do I pay to return items I'm not keeping? Nope! �We include a USPS prepaid return mailing envelope in your Dia Box. Related articles What do I do if I didn’t receive a prepaid return mailing envelope? I love something in my box but it doesn’t fit. How do I request an exchange? How do I mail back my returns? Do I need to pay for shipping on a size exchange? Can I return an item that I’ve purchased through a size exchange?