Nice way of marketing! What is this script or wordpress plugin? Need Help. You want to know too!

I’m looking for a particular script found on a website but I can’t seem to name it. See the script here What powers that little pop-up offer with the envelope on the bottom right (with the offers)? Is it some kind of wordpress plugin or javascript? How can I replicate it for my website? Please recommend a script or preferably a wordpress plugin that has this functionality.