Leather uses a prong collar, and it works great! It worked wonders on Timber too! They aren't uncomfortable AT ALL unless the dog pulls, which is the point of course! You want a puller to feel discomfort when they pull. Some people will tell you not to use them because they cause damage to the throat -- but the damage is only slightly worse than what a regular collar might cause, and not serious at all.

It's a great teaching method, give it a try!