Prong Collar

Velcro dog is easy enough to teach. I can off-lead heel any of my dogs through chaos, and if strangers are around you'd have use a crowbar to remove Baxter from my side (he thinks it's his duty to protect me). You just start out by rapid-fire feeding of treats whenever the puppy is in heel position, then work from there.
 
It's also possible the dog was trained using force or an ecollar, but once a dog is trained you don't need the equipment anymore; they're called "training devices" for a reason.

Thanks for all the different opinions, they have really made me think.   Since my first post I've done some expirimenting and realized that I may have jumped to some conclusions before! 
 I took my other dog out for a walk with no prong collar and tried to get him to sit and then reached down to touch him, and guess what, he stood up. I don't think what I was doing before was making my dog stand up, I think that since I taught them with treats before, and I usually do give them a treat for sitting, or their dinner, etc. normally I release them as I reach down and hand them their treat...so they're used to standing up when I reach toward them....I worked on having them sit and petting before I release them and this has seemed to improve  (although I'm still not doing the collar thing when the dog's sitting, I don't like that and I don't think it's helping anything).
Second, I guess  he has matured some or calmed down some since I last tried to work with him on this because i decided to get out my treats again, just regular pupporonies, (I was using lunch meat before and he ignored it!)  and surprise, he took them!  It was just walking around the neighborhood, not like with a lot of people around, but still he would not do this before.  
Third, after trying out the prong collar for a good week and a half, I can't see any signs of rubbing or poking on his neck, nor does he seem to mind anymore when I put it on or take it off of  him ( now that I have the hang of it, it goess on and off much more easily).....On his flat collar he would hit the end of the leash (4') and choke and gag, but he still kept doing it, with this he stops before he gets to the end of the leash, and i guess i would rather him feel discomfort and stop  than to continue to do something that really seems to be hurting him.    I did take him for a few walks without the prong since then while I was trying to decide what to do and he really did much better than usual, so i don't think he will have to use it very long, and I'm only going to use it for heeling/walking.  Thanks for all the input

On his flat collar he would hit the end of the leash (4') and choke and gag, but he still kept doing it, with this he stops before he gets to the end of the leash, and i guess i would rather him feel discomfort and stop than to continue to do something that really seems to be hurting him.

 
I think were I in your position I would feel the same.... I have not been in this position because I've always had the luxury of raising a dog from puppyhood and preventing the pulling rather than having to get the dog to "unlearn" it later, which is much, much harder.  I don't like the idea of using pain or discomfort to train a dog if there are other methods available, but I would rather a little discomfort than a whole lot of long term damage.  I would exhauist those "other methods" first though.

Ok, you guys are right I'm not going to take him to that class again.  See the thing is, he sits when he feels like it and in class he's more distracted by the other dogs and not very motivated so he'll do it a couple of times for a treat and then he could care less about the treat, as before.  The guy keeps insisting that I need to find a way to put him in a sit, which stresses my dog out and doesn't work, he's a little dog but u just couldn't do it if you tried. And the guy's all like "we should set u a private lesson to work on this"  No way am i giving him more money!  The only reason I signed him up for the class in the first place is the guy runs free socialization classes on the weekends for his clients which is very convenient for me because there's not a dog park close by and so that he could have more practice in a controlled environment versus some place like petsmart or out for walks. 
Some of the other posters suggested releasing him to go do what he wants as a reward, and i've tried this, and even though it may take him 5 minutes to decide to sit, he eventually does it when he realizes he can't go anywhere till he does, and since i've been practicing on walks more he is getting slightly faster.  I hardly bothered to ask before because I had heard not to ask unless a. i knew he was going to do it or b. had some way to enforce it. And since I had no way to enforce it, and I was pretty sure he wasn't going to do it, I gave up asking. But maybe he just needs more patience and evetually he will sit a) more quickly b) more reliably and c) when there are people there.......actually i really don't even care if he sits at all, it just seems like a good way to keep him from running up to people until its ok for him to do so. 
I just want to be able to take him more places with me.   He really is a very good dog, last night after the socialization part of class he was still on the other side of the yard chekin out another dog and I called him to me and he came running     He's just a little special. Anyway, thanks for all your posts.