Abstract: Example rocker reducer instruments securely engage a receiver that is implanted in a vertebra of the spine and move a spinal fixation element, such as a rod, into a channel formed in the receiver. Example instruments pivot around their contact point with the receiver and a cross-pin or foot feature on the instrument makes contact with the spinal rod and applies a downward force to reduce the rod into the receiver. Further, example instruments can contain a stopping mechanism to limit the amount of compressing force applied to the receiver while maintaining the instrument in a rigid, closed position.