Tired of the dog pulling, well we got the answer. This collar is made to tighten up and turn hard to control dogs. I like this style with the buckle best for control. 
The Martingale collar is made to tighten up as the dog pulls and quickly realizes you are in control. Very handy for training especially since the dog soon learns that NOT pulling gives him more freedom. I can't watch owners who just allow their dogs to pull them along instead of being in control.