As far as I know it was supposed to help keep the dog from trying to pull and drag the person trying to walk them. The dog my daughter and son in law had was very hyper and this was supposed to help that. I hope this helps. Thank You for stopping in and God Bless.
Yes, I know for sure it will fit a 45lb dog. My daughter and son in laws dog was around 60lbs. I think this one clips on top at the base of the neck. I am not sure. I added two more photos to try and help you see more detail. I hope this helps.