that you exchange books for books rather than credits. It saves you and the othr member credits and postage.

You order a bunch of books ou want from a boxer, then they go to your shelf and pick however many of yours they like. If it is less than you chose of theirs than you just tell them which ones are your priorities.

THen they ship your box tyo you and you ship theirs to them. No credits exchanged and less spent on postage.

From the help center:

Box-O-Books lets you ship books for less money, and no credits are needed.

Why use Box-O-Books?

• It saves you money!  Sending multiple books in one shipment costs much less in postage than sending single-book shipments.
• It saves you credits!  When you don't have any credits, you can still get books!
• This service is especially useful to new members; they can swap whole boxes of books with other Boxers, thereby replenishing their library while waiting for their newly Posted books to be requested and earn them credits.
• Box-O-Books is the only way that PBS members are permitted to swap "books-for-books" without using credits.

Box-O-Books is a paid subscription feature at PBS

•  Enrollment in Box-O-Books  is $8.00 per year
  • Box-O-Books can be purchased in the PBS Kiosk.
• There is no limit on the number of Box-O-Books swaps you can conduct in a year