It seems to be the first hardware wallet for byteball, isn't it. Did they flash byteball code into arduino hardware to build that wallet?
It's a C++ implementation made from scratch (
https://github.com/Papabyte/byteduino)
It's not a complete featured wallet though (only 40KB of RAM on ESP8266!) but it proves than Byteball can run on hardware that costs only a few dozens of cents. At this price level it's even possible to make disposable sensors that would send only one measurement into DAG during their life.