I use them on both of my girls and we love them. The are nice because you can lock them up close for areas where you want them close and let them have room to explore at the park and such. I have, on occasion, had to pull in the leash and lift Bella by the harness if another dog gets close. But that is rare because the only time I let her that far away is if we are out in an open area.
I have never had either one pull it out of my hand...but I do get them tangled up
