The color image forming apparatus comprises a transfer belt device which feeds a transfer member such as a paper and a plurality of image forming units. In this manner, the spread of critical dimensions of vias around the target value may be significantly reduced while also reducing any maintenance and rework efforts. The OMC is further operable to manage the second wireless network using a second management protocol. Knobs on the sides of the connector provide a convenient gripping surface. In order to improve the efficiency of the stirring device, the invention proposes that at least one propeller be attached to the shaft that, when the stirring body rotates in the rotational direction, generates a flow directed toward the top of the stirring body.