Eldonian Revolver Baucher Bit
The Baucher Bit is also known as the "Hanging Cheek Snaffle". The small rings are attached to the bridle cheek pieces and the larger rings to the reins.
The Baucher Bit allows for a more stable bit in the horses mouth minimizing the movement of the rings and mouthpiece. This bit has a spit lozenge(link) which allows rotation giving the bit more flexibility.