For single books, we suggest a padded envelope (usually available at the Post Office).
Do NOT use a USPS Priority Shipping box or envelope. The Postal Service charges extra to ship these boxes. If you do ship using a Priority Mail box or envelope, the additional shipping cost will be deducted from your order along with $5 per box for processing.
For multiple books, we suggest a small box with enough padding/packing materials to keep the books from moving around in the box.