Just used a kemp controller either attached to a headcollar or a bridle.
Its thinner than a dually and applies more pressure if they pull.
I used one on a nightmare 18hh spoilt brat that the owners couldn’t control even in a chifney and they’d had him since birth.
clipped the KC on and he behaved like a lamb and I was in perfect control. No need for a chifney or anything else
Fairyfeet via Forum