Equipment like that doesn't do anything but put a bandaid on a gaping wound. Rearing is a refusal to move forward. My suggestion is check the saddle and bit to make sure it isn't creating pain in the back or mouth. If a horse cannot avoid bit pain, it's only option is to go up.
Begin with longe work and get the horse moving forward, forward, forward. Change up the routine and let it use its mind. Several serpentines with circles and change of direction keep the horse's mind active.
Finally, if this had now become learned behavior you're going to require professional help. If a situation like this continues, the horse is ruined and becomes a danger.
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