Next to your helmet, a frontal head restraint (FHR) is absolutely the most important piece of safety equipment you can buy.  Below is a short video demonstrating what an FHR, frequently referred to as a HANS device, does (limit the directly forward motion of the head) and doesn't do (keep you from touching your chin to your chest - it isn't designed to nor does it need to do that).  In the video you will see why we feel this is so vitally important to participants in all types of racing and trackday events.  When compared to a set of tires, even the most expensive FHR is an inexpensive, one-time investment and it can save your life.  Please, at least invest the four and a half minutes it takes to watch this video.  You will be glad you did.