Amazon always offers a free one-month trial of its Audible audiobook service, but for a limited time, they’re also tossing in an extra free book credit to sweeten the pot. That’s in addition to the book you normally get with the trial, and each credit is valid for any title in the Audible library. The best part? The books you choose are yours to keep, even if you cancel the trial before it renews.

Just note that this deal is only valid for new Audible members only.