In short, it's a wearable band that uses electrodes to measure your forearm muscles' activity (electromyography, or EMG), coupled with accelerometers to capture motion. It's awesome technology, but contrary to all the "neuro" buzzword bingo, you can't "control computers with your mind" – you have to physically contract the muscles in your forearm, just like if you were using a mouse or keyboard. This video gives you an idea of what the device is actually capable of: https://www.youtube.com/watch?v=oD4efk8T2X4
Either way, it's exciting to see this kind of tech make it into the consumer space. Even if it doesn't catch on with AR/VR, it will have a lot of positive effects for researchers as well as for users with accessibility and mobility challenges.