I used it on a just broken horse as I was advised to use a standing martingale on him as he had a high head carriage. but i found a standing martingale too restrictive so used a MH. Set properly it only comes into play when the head raised up too high. Stopped using it after 2 months as he seemed fine...
I don't normally like using them on one so young but every horse is different!
works a treat and the harbridge is designed to be used whilst riding, plus it gives a horse the option to resist or be rewarded - unlike blankety-blank-blank draw reins !!
I personally do not like gadgets, they more often then not cause muscular and psycological tension in the horse. If you need something to make your horse keep his head down or, by mechanical means, force him into lateral flexion, then there is something wrong, either with you or your horse (mentally and/or physically).
Take away the gadgets, nosebands, martingales, crude bits etc. and what do you end up with? The truth.
Your horse's resistances are feedback, don't try to cover these up using forceful and unnatural means.
Sorry for the negativity, I wish you well with your horse.
I can't bear Harbridges. In my opinion they are one of the most god-awful inventions. Oh and I have one! Lying in some box somewhere gathering dust, it won't ever go on any of my horses again.
Yes I love MH's. They are about the only gadget that I am happy to use. The other reason I am happy to offer them as a suggestion is because even a numpty can use one without doing any damage. (Not that I am saying anyone on here is a numpty of course; just making a point that they can