Abstract: A rotor-stator assembly includes a rotor and a stator, each of which has a plurality of teeth wherein the height of the teeth is less than approximately one twentieth the diameter of the rotor-stator. According to a presently preferred embodiment of the invention, the height of the teeth on the rotor-stator is approximately 1/48th the diameter of the rotor-stator. A twelve inch diameter rotor-stator having teeth 1/4" high can be rotated at 3600 rpm with 40 HP when mixing materials with water-like viscosity. The arrangement of the teeth on the rotor-stator is preferably concentric with radial grooves, but angled grooves may also be used. The teeth my have a triangular or square profile and the dimensions of the teeth, other than their height, may vary considerably.