Upsell Forms are a powerful tool to provide your customers with products or services that are logical add-ons to their purchase.
Upsell forms are used only after a successful Order Form has been processed. Your customer has an opportunity to buy another product or service seconds after submitting the order, when they are the most receptive to the idea.
Upsell Forms make it easy to purchase because the credit card information is still cached and your customer only has to click a "Yes" or "No" button to accept or reject your offer. Read more about Upsell Forms here.