My trainer mentioned trying a running martingale on my jumper who sometimes likes to throw her head up and get all hollowed out, just as a training aid. She told me to get the martingale as well as a breastplate, but since I've never used one before on my mare and it may not work, I don't want to spend an arm and a leg buying new items. I noticed some (like this one) come with the neck strap, would I really need to get a breastplate to use instead?
What are the advantages/disadvantages to having one?
HDR Advantage Flat Running Martingale - Horse.com