experiencing -- you're being concussed. >> it's not a diagnostic tool. it measures force of impact to the head. it identifies significant impact and puts you on a pathway to be assessed. it gives you an extra data point that elise talks about. >> brian: how does it go on? you wear it like a hat, you can wear that under a helmet? >> it fits under any kind of helmet or nonhelmetted sports. as a parent, buy it for football season and you can put it on your head when they're going out for a bike ride, skiing, any type of activity. >> elisabeth: rough housing with their brother in the basement. >> brian: you can put it on by the touch, right? >> yes. >> brian: what are we looking for once you put it on? >> in the back of the skull cap, this hangs below the helmet, above the shoulder pads. you'll see there is a green light right now. that just signifies that the unit is on and functioning. when the device sustained a moderate impact, a yellow light will start to blink and a severe impact, a red light will start to blink.