The Pessoa bit is a well-known variant among elevator bits, designed for the mouthpiece to be able to move vertically along the bit rings. When a rein aid is given, the mouthpiece will elevate towards the corner of the mouth, while the cheek piece will press in against the horse's cheek. This creates a pressure both inwardly and upwardly, helping to control and lift the horse's head.
Forward/downward and in turn apply pressure on the horse's neck. The Pessoa bit is designed with a small ring at the top where the cheek piece is attached, a large ring in the middle, and one or two small rings below the large one. How sharp the bit acts depends on which of the rings you attach the rein to. The small rings below the large one can be said to correspond to the shanks of a leverage bit. The longer the shank, or the lower you attach the rein, the sharper the bit's effect. For the Pessoa bit, one usually uses two reins or a rein connector.
How it works If you look at a Pessoa bit from the side during a halt, you can see that the rings below the large ring move backward/upward, and the small ring above the large one moves forward/downward. This rotation causes the cheek piece to move forward and downward, in turn applying pressure on the horse's neck. The difference here compared to a regular snaffle bit where the cheek piece is in the same bit ring as the rein is that with a snaffle bit, the cheek piece becomes slack when you apply pressure on the bit. Elevator bits and Pessoa bits are not for beginners and require an experienced rider to be used correctly and without risking harm to the horse.
Difference from leverage bits The main difference between elevator bits and leverage bits is that elevator bits do not come equipped with any chin chain or curb strap which appear in various variations on leverage bits. The chin chain is there to soften the leverage effect, distribute the pressure, and limit how strong the leverage action can be. However, on the Pessoa bit, you can attach a strap to the topmost small rings which runs behind the horse's jaw; this then acts similarly to the chin chain, and depending on how tightly it's fastened, can limit the leverage effect.