I have one for Kai. I only use it when we don't walk at busy places. He tries to pull back when we're around places he's not use to, including busy roads/sidewalks. He can slip out if he really tried. He's done it before.

At first, Kai didn't like it but he thought differently after a few sticks of pepperoni. If you haven't taken it back yet, why don't you just let her wear it in the house for a while? Just let her get use to it. Then you can walk around the yard or something with a leash attached.

Anywho, I love my halti. The only thing I don't like is that Kai can slip out with some tugging. Other than that, he walks WAYYYYY nicer. It's so much easier to walk with him when he's wearing it.