I am probably going to order one, just to see. I have had success with the metal ones for training. They actually have a patented name -Good Dog Collar, I finally found them . Here's a picture.


I don't really like 'obedience' training with a buckle collar, as it provides no real correction. Looking at it more closely, I don't know how effective they would be with longer haired dog, or if they would snap if a heavy dog lunged on it.
They are also much cheaper than the metal ones, as the one I have is huge (I can fit my akita x in it).