YouTube has introduced Bumper Ads, a six-second ad format aimed specifically at mobile.

The short ads appear in-stream but, unlike YouTubes flagship TrueView product, cant be skipped by viewers.

Bumper Ads are ideal for driving wide reach and frequency, especially on mobile, where “snackable videos” perform well, says YouTube, and claims that the format works best paired with longer TrueView ads to create a broader campaign.

“In early tests, Bumpers drove strong lift in upper funnel metrics like recall, awareness and consideration – complementing TrueView’s strength in driving middle and lower funnel metrics like favorability and purchase intent,” said video ads product manager Zach Lupei.

Two brands involved in these early trials were Audi Germany, which cut up its longer ad creative, and Atlantic Records, which used the short timeframe to highlight a single guest vocalist on Rudimental’s second album.

Bumper Ads are available through through the AdWords auction on a CPM basis.