This format is a mobile-optimised banner. These ads have been shown to work well as a large smartphone ad format, particularly when used at the bottom of a page. Suitable for mobile text and display ads.
You need this to get it done:
You can create a responsive display ad, or upload a display ad. You can also choose to copy existing ads.
You can upload image ads as .gif, .jpg and .png
You can upload AMPHTML ads as a .zip containing 1 HTML document and up to 39 media assets.