The paper presents a theoretical and experimental investigation into a dual rotor magnetically geared power split device for hybrid electric drivetrains. It is shown that the modulation of the permanent magnet field results in two dominant space harmonics, thus, special attention should be given to the design of the stator and the selection of the winding configuration. A prototype is designed, and tested, the operation as a power split device is demonstrated and it is also shown that efficiencies in excess of 94% can be achieved.