This thing works wonders!! I got one for Otis since he is a puller when out in public and it works great! He can still pull if he really wants to, say if a dog is nearby! haha But, you have control over it. He can't pull you down on the ground or pull your arm off. He doesn't try to pull because it is uncomfortable. It fits them right under their armpits and when they pull it makes it very uncomfortable. It has to be fitted properly and you need to use a short lead, otherwise it won't work properly. Fortunately, I have a store here in Reno that sells them, so they were able to fit it for me. But, I understand that SENSE-ation won't sell to retail stores, so you either have to find a representative in your area (usually a trainer) that does sell them or order it directly from their website. My friend in VA just ordered one for her boxer, and I sent her pictures of Otis wearing his so she could get an idea as to how to put it on.
Anyway, hope this helps! Feel free to PM me if you would like additional info.