A magnetic gear assembly comprising: a plurality of inner permanent magnets; a plurality of outer permanent magnets located concentrically with respect to said inner permanent magnets; a modulator (50;150) located between said inner and outer permanent magnets (30,40) and configured to modulate the magnetic fields produced by said inner and outer permanent magnets (30,40), wherein said modulator (50;150) comprises a plurality of laminate plates (100;200), and each plate (100;200) comprises a ring having a plurality of regularly spaced substantially solid portions (102;202) joined by hollow connecting portions (104;204), wherein each plate (100;200) is connected to an adjacent plate (100;200) by a connecting means that is formed from or uses the material of the plates (100;200), such that the laminate plates (100;200) form a mono-structure held together by the material of the plates (100;200), wherein said plates (100;200) are stacked together such that said solid portions (102;202) align so as to form a plurality of magnetic portions of said modulator (50;150), wherein the hollow connecting portions (104;204) are stacked together and align to form the substantially non-magnetic portions, wherein the hollow connecting portions comprise metal connectors (105;205); and an input shaft and an output shaft, wherein one of the input shaft and the output shaft comprises lips or extensions that cooperate with and extend into air gaps in the modulator (50;150) in order to hold the modulator in position so that, in use, the modulator (50;150) has slid into the lips or extensions and rotates with the input shaft or the output shaft without the need for e.g. bolts or clamps, wherein the hollow connecting portions (104;204) are void between the connectors (105;205) to provide the air gaps. a plurality of inner permanent magnets; a plurality of outer permanent magnets located concentrically with respect to said inner permanent magnets; a modulator (50;150) located between said inner and outer permanent magnets (30,40) and configured to modulate the magnetic fields produced by said inner and outer permanent magnets (30,40), wherein said modulator (50;150) comprises a plurality of laminate plates (100;200), and each plate (100;200) comprises a ring having a plurality of regularly spaced substantially solid portions (102;202) joined by hollow connecting portions (104;204), wherein each plate (100;200) is connected to an adjacent plate (100;200) by a connecting means that is formed from or uses the material of the plates (100;200), such that the laminate plates (100;200) form a mono-structure held together by the material of the plates (100;200), wherein said plates (100;200) are stacked together such that said solid portions (102;202) align so as to form a plurality of magnetic portions of said modulator (50;150), wherein the hollow connecting portions (104;204) are stacked together and align to form the substantially non-magnetic portions, wherein the hollow connecting portions comprise metal connectors (105;205); and an input shaft and an output shaft, wherein one of the input shaft and the output shaft comprises lips or extensions that cooperate with and extend into air gaps in the modulator (50;150) in order to hold the modulator in position so that, in use, the modulator (50;150) has slid into the lips or extensions and rotates with the input shaft or the output shaft without the need for e.g. bolts or clamps, wherein the hollow connecting portions (104;204) are void between the connectors (105;205) to provide the air gaps.