Web Profit Doubler can be used to show any sort of secondary offer.
However by far the most powerful use of the software is to show what’s called a “Reverse Squeeze Page“, offering visitors a free gift in exchange for subscribing.
Reverse squeeze pages are exactly the same as conventional squeeze pages, except for when they are shown.
Conventional squeeze pages are shown before visitors see the sales page, forcing visitors to subscribe before they can even view the sale page.
If visitors decide not to subscribe, they will never even see your sales page.