This small gripper uses a rack and pinion design with a servo-driven pinion and opposing racks to keep the gripper paddles synchronized and parallel to each other throughout its 32 mm range of motion. It includes a special micro servo with an additional wire that gives access to its feedback potentiometer, so you can track the actual position of the gripper paddles. This product is a kit, and assembly is required. This same gripper is included as part of the Robot Arm Kit for Romi.