This is an old steel horse bit with a dark patina.
Its mouthpiece has a single joint,
There is a small ring attached to each end of the mouthpiece.
There are two large "cartwheels" with various divisions loose on the mouthpiece.
"Professor" Jesse Beery (1861-1945) was an interesting man.
He was the son of a farmer and became a famous horse trainer, starting the Jesse Beery School of Correspondence in Horsemanship in 1905.
The course was published in eight volumes and a certificate issued to the student on completion of the course.
It is still available today.
Back to the bit. As its name suggests depending on how the reins are attached it can function in different ways.
At its mildest the rein attaches to both the small outer ring of the mouthpiece and the large divided ring at the same time - so the bit functions as a simple jointed snaffle (with cheeks)
If the headstall is attached to the large rings and the reins to the small rings it must function rather like a Wilson snaffle, although those large rings could put a lot of pressure on the sides of the mouth.
The third position for the reins attaches them to the front of the large rings and the small rings at the same time, which must have produced a severe pinching action.
The fourth position had a different arrangement on each side, presumably to correct leaning or some other problem.
The Beery family sold their business in the 1970's but the books are still available through www.jessebeery.com
There are no maker's marks or stamps.

Dimensions : Mouthpiece 5¼" (13.5cm), Large ring diameter 3⅜" (8.8cm)
Weight : 339g (12oz)