Holding the bit in place: They ensure the bit sits at the correct height and position within the pony's mouth, which is crucial for comfort and effective communication. Communication and control: Along with the reins and the bit, the cheek pieces allow the rider to apply pressure (when using the reins) to guide the pony's movements, either for turning or slowing down/stopping. Stability and fit: They are adjustable to ensure a secure and comfortable fit for the individual pony, working with the browband and throatlatch to keep the entire bridle system stable on the head.