Magnetic rotor, which is made from segment magnets glued to the inside or outside the steel sleeve, is a important part of motors. This motor part are widely used in stepping motors ,BLDC motors, PM motors and other motor application. 

The magnetic outer rotor is relative to the stator, it works outside. The segment magnets are glued to the inside of steel sleeve then rotates surround the stator. It also acts as an insulator. The primary advantage of an outer rotor motor is relatively lower cogging torque.