I actually sell them...they work very well!! You have to be on level ground to effectivly use them and since they are an inclinometer they dont work unless you are in a tree, but they are very accurate and simple and they also act as your haul line...really a neet idea.
You probably would not buy it...you would buy it INSTEAD of a laser. It is more for those who cant afford what some of these lasers are going for but still want accurate yardage.