Jumping Safety Vests

My daughter is going to start her jumping lessons again when the weather breaks. She had just started in the fall of last year before the season came to an end due to the deep freeze we were in.

I am thinking about getting her one of those protective body vests. I've seen them on some equine sites. Some seem to be just foam - is that enough to prevent a broken bone?

I don't know anything about them. That makes it hard to know what I should be looking for.