Our class which starts this Sunday is only a flat collar (no pulling) or a harness (no pulling) for class, it is a positive class and you teach the dog through commands and praise and treats, not with pain and punishment or head jerking - Jesse is 6 months. I have been walking Jesse since he was 8 weeks old, I had him heeling at 14 weeks 2 walks a day were controlled and 1 walk a day was loose leash or loose. For the last month we now use just a harness, and a retractable, he knows he must heel on roads and sit at roadways and once in the park he gets loose leash walking (no pulling). We trained Jesse not to pull by doing the following: If he got out of a heel then I would stop and freeze, once he got back to me we would start again. He soon learned that if he wanted to go forward he must walk beside me. Same thing on retrackable, if he hits the end and pulls, I freeze in place and say nothing he has to walk back to me to continue on - first few days we didn't get far very fast but he caught on. I went to view another obedience class that I was thinking about but they use chockers and I viewed some nasty punishments in class and decided no way I want to be a part of that. I believe that with a GSD if you treat it with kind words encouragement, praise for doing good, ignore the bad or just say "no" and redirect you will get a wonderful trustworthy dog, if you treat it with abuse, nasty words, kick it, hit it, force it, you could end up with a untrustworthy dog. Just my two cents.