The Cavity Transfer Mixer (CTM) was primarily designed as a distributive mixing device to be used as an add-on unit to existing extruders. Understanding the flow patterns and characteristics within the CTM is of fundamental importance for a proper design and optimum processing. Due to the complex geometry and the transient characteristics of the flow, solving for the flow patterns in the CTM is not an easy task. However, some of the design features of the CTM can be reproduced in a simplified device which will allow more detailed experimental and numerical investigation. In this work such a simplified device was built and used to reveal some of the features of the flow patterns and the influence of one design parameter (cavity shallowness) on the dispersive mixing efficiency.