Twitter is testing full-screen mobile ads in Fleets, which are disappearing video tweets, after seeing advertisers’ interest in the format on rivals like Snapchat and TikTok.

On Tuesday, Twitter announced that it would start showing ads in Fleets to a limited number of users in the U.S. These disappearing video tweets are more private and feature some of the same tools people find on apps like Instagram, TikTok and Snapchat.

Twitter launched Fleets last year, but it has largely been considered a niche feature. The company has never said how many of its 199 million daily users create videos there. However, Twitter said in its announcement on Tuesday that the ad test in Fleets has broader implications for the platform.

“As we experiment on this new surface for ads, we’ll take a close look at how vertical, full-screen ads perform on Twitter,” the company said. “We want to understand how this content performs for customers not just for Fleet ads, but for future iterations of full-screen formats on Twitter.”

Twitter has been updating its entire advertising business to help brands improve performance. For instance, last year, Twitter updated its ad-targeting capabilities to entice more direct-to-consumer, e-commerce and performance-driven brands. Full-screen ads are another step to catching up with its peers on a format that has proven successful.

Since 2015, Snapchat has been a pioneer in full-screen ads, pushing vertical videos as the preferred method of watching on mobile devices. TikTok has taken the format and made it a key component of its pitch to marketers. Brands have adapted to the full-screen method of creating ads, seeing a format with many upsides. For one, the ads fill the whole device, keeping a person’s full attention. Also, people watching videos in messaging apps often have the volume turned on, giving brands the ability to play with sound.

Noah Mallin, chief brand strategist at IMGN Media, says that even if Twitter Fleets don’t have a large audience, brands could still be willing to experiment. “The play here is [to say], ‘Well, you have the story creative anyway from Instagram, Snapchat and TikTok, why not add Twitter to the distribution,’" Mallin says. “And they may get a few takers.”

In its announcement, Twitter highlighted how a few brands have created Fleets already, including Disney and Wendy’s.

Twitter has stepped into audio, as well, with the full launch of Spaces last month. Spaces is a livestreaming audio section where users can start chatting to groups of followers, similar to the app Clubhouse.

“We can see how this would work well alongside Twitter Spaces,” says Joshua Lowcock, chief digital and global brand safety officer at UM, speaking of the potential for brands to explore Fleets and Spaces. “Advertisers are always keen to test ad formats, like Fleets, that use the Stories format. I have been really impressed with the pace and quality of ad and product innovation coming out of Twitter in the past several months.”