An agitator comprising a rotatable impeller comprising blades, magnets, and a shaft, wherein the impeller is configured to be driven by a drive unit magnetically coupled to the impeller, and an impeller seat receiving the rotatable impeller, the impeller seat comprising an upwardly arranged cylindrical housing, a flange, and a base, the cylindrical housing comprising a central opening for the impeller shaft, and the base comprising a collar and pins arranged to engage with a locking and centering mechanism, as well as a mixer engagement unit including the agitator, a mixer system, a mixing vessel, and methods of using the agitator, mixer engagement unit, mixer system, and mixing vessel, are disclosed.
