With Hover Zoom activated, you an move your mouse cursor over a thumbnail images on an image and see the full-sized version of the image in an overlay.
Hover Zoom works on all popular sites from Flickr, Twitter, Amazon, eBay, Instagram, Pinterest, Google Images, Wikipedia, Imgur and many more. You can also press the S keyboard shortcut to save the linked image.
It can also display text captions for Facebook albums and some other sites.
The extension is ad-supported and may insert affiliate links and ads in your web pages. You can however turn it off from the options window.