 And does that tell you how much activity there is in a particular part of the brain? Yes, exactly. So maybe if you're doing some hard mathematics, you'll see in the prefrontal cortex, like a sudden intake of oxygen when it demands the oxygen. And then it will see the blood flow past, which will be the used oxygen afterwards. And what do people tend to buy them for? Well, that's a very good question. So we've been using this to study how hard it is to do different types of tasks in manufacturing environments. But now we're very interested to know, now that you can buy these devices for yourself, it becomes very much a personal data issue.