Google on Monday again teased its upcoming Pixel 4 phone, which it's expected to announce sometime this fall. It follows a similar tweet posted in June that first revealed the phone.

The company posted a short video on Twitter showing how users will be able to control the phone without touching by using hand gestures. It also explained how the feature works in a blog post.

The clip starts by showing a user unlocking the Pixel 4 by looking at it, similar to how Apple's Face ID works on the iPhone. Traditionally, Android phone face-unlock mechanisms haven't been as secure as Face ID, and Android phones have instead relied on fingerprint readers for security and face unlock for convenience. Google says this is more secure now.

"Face unlock uses facial recognition technology that is processed on your device, so that image data never leaves your phone. The images used for face unlock are never saved or shared with other Google services," the company explained.

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The video also shows a user skipping songs in an app without touching the phone, again suggesting the front-facing camera is more advanced than usual.

The option is called "Motion Sense" and uses radar technology called "Soli" that was developed by Google's Advanced Technology and Projects team.

"Pixel 4 will be the first device with Soli, powering our new Motion Sense features to allow you to skip songs, snooze alarms, and silence phone calls, just by waving your hand," Google said. "These capabilities are just the start, and just as Pixels get better over time, Motion Sense will evolve as well. Motion Sense will be available in select Pixel countries."

The Pixel 3 and Pixel 3 XL were launched last October, when Google traditionally releases its new phones. The Pixel 4 and Pixel 4 XL are expected around the same time.