A button ad is an optional, add-on service to the basic listing of always-free eBooks. You should purchase a button ad if you’d like more exposure for your eBook, even after other eBooks are posted and push your listing off the homepage.
A button ad is 125px wide and 125px high, and it appears in the sidebar of almost every post and page.
Button ads rotate in and out with other button ads, and only four button ads show at one time.
Button ads appear in the sidebar for 15 days or 30 days and can be extended, but they do not auto-renew.