This is an antique bit, but the style is still very common today. The shanks of this curb bit are S shaped. There is a medium port (the upside-down U in the middle of the mouthpiece). The shanks are fixed to the mouthpiece.
This type of bit is commonly used in Western style riding. As a curb bit it will encourage the horse to lower its head and flex at the poll.
How it Works:
This bit is a leverage bit. The rider’s signal is felt in the mouth, over the horse’s poll, on the chin through the curb strap or chain.
A low port makes room for the tongue and prevents the horse from putting his tongue over the mouthpiece. Higher ports on a curb may place pressure on the palate and increase the pressure on the bars of the mouth. The leverage action of an S shaped shank will be slightly different than a bit with straighter shanks. The weight too will make a difference to what a horse feels when the bit is activated.
From the collection of Rose Danko, Coates Creek Stables