ADT-2 Android TV developer device is Google’s mystery 4K HDMI dongle

Last month, we saw a teardrop-shaped G-branded dongle appear at the FCC with few details. The HDMI device was featured with a remote control, USB charger, and a "4K ATV Stick" label. Though somewhat shaped like a Chromecast, the Shenzhen SEI Robotics company listed on the FCC filing raised doubt over whether it was actually a Google device. Now we know the answer.