With this product-specific custom field you can add an additional hover image to the product listing. It is displayed when the mouse is moved over the cover image.
You can find the "Hover image" custom field in the respective product:
Tab "Specifications" ⇒ Block "Custom fields" ⇒ Tab (Set) "Products (ThemeWare® ... Pro)"
Type: Media selection
Technical name: twt_{theme}_{edition}_custom_field__product__hover_image
Guide: You can find a step-by-step guide in the ThemeWare® Wiki: