There are a number of MIDI rings on the market. IK Multimedia makes one and so does
But there are a number of unique things about the new Genki Instruments Wave. It was designed in Iceland and was first used on stage at the at the Iceland Airwaves music festival. Genki is also the only Icelandic music company with a Japanese name (Genki means healthy in Japanese!).
Wave is an Indiegogo project and has already passed it's funding goal. It's scheduled to ship in December 2018.
Here are two Youtube videos showing what the Wave can do.