I used one on Roxey when she was young and it worked wonders. After just a few lessons she was great. I do use a choker when we go out for walks because if she decided she REALLY wanted something she could slip right out of her regular collar.

I use one on Bon now because he is such a big boy and a lot to handle. I feel much more in control. I've thought of trying a martingale collar but I'm not sure where I could get one to slide over his big ol' head