I am researching bits and their functioning, and I am a tad confused on these types of shanks.
The ring right by the mouthpiece; what is its purpose?
Is it a place to put the reins and use the mouthpiece without leverage?
The higher and longer the shanks, the harsher the bit. The center ring is the mildest and puts less pressure on the horse. Place the bit in your hand, balance it, ties something to the rings at the bottom of the shank and at the center. Then pull , you should feel the difference, now imagine this in your mouth pressing on your gums and tongue. The shank at the top the longer the shank the more pressure on the poll. Hope this helps some.
Those styles can also change the balance of the bit by the weight of the "rings" next to the bars.(as does the sweep in the shanks) So rather than that bit hanging a little more straight up, with the rings it creates a little weight behind the shanks allowing for more signal before the pull and allowing a horse with a more horizontal rather than vertical headset find the balance or neutral spot in the bit.