How does it work?
At the practice range, place the Head Down system opposite the ball inline with your eyes at address. Start with short irons to get the feel of action. The device works whether you are chipping/pitching or striking a full shot (it also has a setting for putting on the green).
Hit down on the ball with your normal swing pattern. You will see a random image flash for a half second if you kept your eyes in the area at and briefly after impact. With practice it will become second nature to identify the image before release to watch your ball. You should find your shotmaking becoming more consistent as you stay down through impact.