While most snaffles have a single joint in the center, there are some that have more than one joint. Collectively, they are known as the multi-jointed snaffles.
This particular bit has a French Link mouthpiece. The French Link is a small flat, peanut-shaped link in the center of the mouthpiece. It lays flat to the bit, as opposed to the Dr. Bristol in which the link is at an angle to the rest of the mouthpiece.
The french link doesn't have the nutcracker action of a single jointed snaffle and therefore may be a good choice for horses with a low palate. Instead, the mouthpiece lays flat across the tongue. Obviously, there is a lot more mobility within the mouthpiece, and so, some horses that may get "set" in a single jointed or mullen-mouthed bit, may go lighter and lean on the bit less in the French Link.
It should be noted that horses with large or sensitive tongues may not like the french link snaffle because of the close contact of the bit with the tongue.