well, we got a 4 year old Dogue de Bordeaux about 155lbs, good looking dog but very very dominant dog. it came into play whenever he noticed another male dog around him and then the fight begins (me trying to hold him away it is) we have encounter sit on spot on our local car show which takes place every sunday and i saw a guy walking his mastiff there with such ease, to be honest i envied him, so i approached him and sure enough he is the owner and head trainer of sit on spot... he came to our house the next Tuesday and demonstrate to us the work he is doing with our dog and boy i was in for a surprise. after 20 minutes the pulling was a thing of the past even when his dog (male) was next to my guy, that was really something. it defiantly worked fantastic for me and i became a customer of them. i dont want to make it look like it was some kind of magic because after they show you what to do, you do need to work with your dog! the good thing is that they make it so much easier on you and way faster that you would ever think. after about six weeks that i am working my dog for about 15-20 minutes a day on the things they showed me i have a 100% better dog then what i had two months ago. great job sit on spot!