Google launched a new search ad format "Mobile Ad Sitelinks" globally on high-end mobile devices. Ad Sitelinks displays additional links to content located deep within your website, to introduce customers to multiple landing page options for your site. mAS function similarly to Ad Sitelinks on desktop, currently, only two-line sitelinks will appear on mobile devices, with each line displaying one sitelink," informed Google.
To start with mAS -- if you've enabled dAS, your ads will automatically show on mobile phones -- provided your campaigns are opted-in to run on iPhone and other mobile devices with full Internet browsers.
"dAS have been a useful tool for advertisers, leading to an average increase of over 30% in click-through rates. Because websites mayn't yet be optimized for viewing on mobile, navigating them to find info can be more difficult. As a result, we anticipate that mAS will be similarly, if not more, effective on mobile as the benefit of deep linking and driving users further down the conversion funnel is even more valuable," Google said.
More Info: AdWords Help Center