Twitter today is debuting a new advertising format that will encourage its users to tweet more often, while talking about an advertiser’s brand. With the new ads, businesses and brands will now be able to post a call-to-action that offers some sort of exclusive content that can only be unlocked with a tweet — like the ability to preview the trailer from a new film, gain access to an exclusive Q&A, get a recipe from a favorite food company and more.

The feature is an extension of Twitter’s previously launched “Conversational Ads,” which give advertisers the ability to post images and videos along with call-to-action buttons that include customizable hashtags.

The difference with these new “Instant Unlock Cards,” as they’re called, is that users have to tweet in order to view the content being promoted. That is, the content is only unlocked after the tweet is posted.

This is something that could spur Twitter’s user base to interact with the service more often. But more importantly, it could potentially even push people to sign up for a Twitter account, if they were interested in viewing the content from the brand in question.

Boosting user growth is something Twitter desperately needs these days, as its monthly active users grew just under 1 percent in the last quarter, to 313 million. The company has not figured out the secret sauce when it comes to convincing users as to why they need to set up a Twitter account for themselves — after all, Twitter’s content of interest can be viewed by logged-out users, as well, while the most newsworthy tweets eventually make their way into articles that are later disseminated to other social networks, like Facebook, or are shared by news broadcasters on air.

In addition to the possibility of giving users a reason to tweet, the new ad also capitalizes on the type of activity brands try to encourage anyway — that is, to have people tweeting and sharing their message with their friends and Twitter’s wider network.

These promoted tweets featuring the Instant Unlock Cards will appear in users’ timelines and offer explicit instructions on how to view the exclusive content they’re offering. But instead of requiring users to write out their own tweets, there will be a button users can click that will pre-populate the tweet with customized text, like the brand’s custom hashtag.

During its beta trials, Twitter reported that brands saw an average 34 percent earned media rate, it says. That means for every 100 paid impressions, the advertiser saw 34 views. Brands that had early access to Twitter’s new features included Coca-Cola, AMC, Marvel and Axe Body Spray.

AMC used the ad to promote the world premiere of its “The Walking Dead” trailer, which was the best use of the format. Coca-Cola and Marvel simply encouraged Twitter users to pick between two options and then tweet their support accordingly.

Along with Instant Unlock Cards, Twitter says it’s also rolling out more advanced analytics for brands tracking their conversational ad units, which will help them track engagement metrics and earned media associated with their campaigns.