Link to a large image
Assuming these are normal image fields, you can go to Structure > Content types, then select manage display for your product node type.

There, click on the settings button on the right side of your image field. A settings form should be expanded now, where you can configure in which image style you want them to show up and to what they should link. If you choose link to file, clicking on it will link directly to the original file (only).

An alternative is provided by the Colorbox module, which allows to display the images in a popup-like overlay. The same settings form should have more options to choose from once you installed that module.