NOTE: This field is currently used only by the Paypal Upsell-Tree Plugin. If you are not using that plugin, then you may leave this field blank.
If you are using the Paypal Upsell-Tree plugin, then in this field, enter the full URL to your product image.
Example: http://YourSite.com/images/product-image.jpg
The image you enter here will be used by the Paypal Upsell-Tree Plugin on the checkout summary page when showing all of the items about to be purchased by the buyer.