This is the Futaba S9255 Digital High-Torque Servo for helicopter usage.
Comes with heavy duty wiring that can handle higher current loads Ball bearing output shaft Metal gears
Coreless motor, a conventional servo motor has a steel core armature wrapped with wire that spins inside magnets. In Coreless designs, the armature uses a thin wire mesh that forms a cup that spins around the outside of the magnet eliminating the heavy steel core. This design is much lighter resulting in smoother operation and faster response time.