A. Replacing a 3 or 4 way switch with wireless requires one dimmer (DRD4/MRD4) or switch (DRD3/MRD3) and a multi-location controller (DRD8/MRD8) for each additional location that controls the lights. For example replacing a 3 way switch set for dimming requires a DRD4 at one end and a DRD8 at the other end. See Replacing Existing 3-way and 4-way Circuits on page 14 of the Wireless Miro Installation Guide.