Not sure if anyone has noticed but the NOW TV 4K Smart Box is no longer being advertised as able to be bought on the NOW TV website or on the Argos website.
You can still however buy the Smart Stick which comes with either the entertainment, cinema or sports pass.
Indeed, you can however still purchase the box via Amazon.
Personally I thought the box was better than the stick. Plus the option to connect via Ethernet I always did like that.