Review on Master Your Putts with O'BEAM Golf Putting Aid by Jeff Westra

I love o'beam. It works as advertised and the customer service has been very good. The downside is that the battery life is terrible and if you forget to turn it off it will drain instantly. It probably only has around 2-4 hours of battery life before running out of juice; However, it uses typical small hearing aid batteries and is replaceable. Particularly useful for keeping your head still on the backswing, but I've since found that some great golfers (Luke Donald) move their heads on the backswing.