What is JustOneBox
It’s an Android TV box sold as a “fully loaded” streaming device. 
What makes it distinctive: it’s preconfigured (“pre-loaded”) with apps / services that provide many live TV channels, sports, movies, and shows. The marketing claims include “lifetime subscription” (or “lifetime access”) with no monthly fees.
 
How it works & typical features
Once plugged into a TV and connected to the internet, you can use it like any Android TV box, but you also get access to the built-in streaming apps that users say include many live channels.
Some models claim features like “7-day playback” (so you can watch shows from 7 days past), HDR support, 4K or even 6K decoding in newer models.