This last week my GF has been borrowing a Dogtra e-collar from a friend to help clean up Heidi on a few things. It has been working great. So I am going to buy one (e-collar). Well today, our trainer said she had a brand new Tri-Tronics sport basic g3 series that controls up to three dogs that she had won in a raffle that she would sell me for basically half the normal cost. It sounds like a great deal, I just want to make sure it's worth it. Everyone in my clubs uses Dogtra's. I don't know much about the Tri-Tronics. Any info is appreciated.