uBeam is a bit of a mystery in Silicon Valley. The wireless charging company claims to have developed a way to charge electronic devices using ultrasonic waves, for truly cord-less charging regardless of what surface your smartphone is touching. The company has been criticized for avoiding detailed discussions and demonstrations of its technology, drawing comparisons to disgraced blood-testing company Theranos.

But yesterday, uBeam showed off its wireless charging tech at the Upfront Summit in Los Angeles. The demonstration was supposed to be “off the record,” which is a strange thing to tell a crowd of people with video cameras in their pockets. As you might suspect, various video of the demo are now floating around Twitter. Here’s a solid one shot by Zillow Group CEO Spencer Rascoff:

Wireless charging of a phone thru the air. Woh. 1st public demo ever @ubeam #UpfrontSummit pic.twitter.com/I6GZx7KDri — Spencer Rascoff (@spencerrascoff) February 3, 2017

In the video, you can clearly see uBeam CEO Meredith Perry holding what appears to be an Android phone near some type of device and waiting momentarily before a charging symbol appears on the display. Of course, the goal is to shrink down that large box into a device consumers could purchase and keep in their homes.

As Axios points out, uBeam’s ultimate goal is to create a device resembling a small satellite dish-shaped charger, but that may be a while off. There are still a ton of other technical questions, too, as to how the company can overcome the limits of physics to create a product that works consistently as designed. Still, it’s a promising first suggestion that uBeam’s foundational concept is actually sound.