Oh I see..
http://www.ustep.com/index.htm

I thought the laser line would be going out away from the person , so they would would be visually/mentally tracking it to encourage forward motion.
So the line goes side to side across in front of you for 1 step at a time?
You have to look down a lot for it to work or mainly only when you feel a freeze coming on?

For freezing, dads therapist suggested stopping, stand up straight, relax & take deep breath, then step, but he usually uses a rolling walker now 95% of the time.