Two Line IPO Tracking??
 

I have seen this done numerous times, but could someone explain the use of the two lines and how they are applied to tracking training? What's the purpose/pros/cons?

Thanks :)

Two lines are used in training, mostly in young dogs. You attach them to the fur saver links on the opposite sides. They are used to help to "steer" dog to stay on the track. Pros? Another tool, better communication with the dog? Cons? You have to be 100% sure where your legs and turns are...