ZH417-11-18-RO is a conventional hybrid stepper motor. It utilizes a permanent magnet in the rotor. This motor uses a ring magnet in the stator and reduces the detent torque (unenergized drag torque) because the magnetic flux path is able to reach over the stator windings and go through only the outer edge of the rotor. Reducing detent torque improves accuracy, smooth operation and reduces noise. Best of all, modifying the magnet location does not change the dynamic torque.