If your bow unit is a xx8 model, you only need one Ethernet Adapter Cable AS EC QDE and an Ethernet cable of suitable length AS EC XXE (XX=length). If your bow unit is a xx9 model or newer, you will need two Ethernet Adapter cables and an Ethernet Cable of suitable length. If you are adding a second unit and the Ipilot/link then you will need to add an Ethernet Switch AS ETH 5PXG. The built-in transducers on the TMs are only 2D and do not provide imaging. They are sometimes optional when ordering the TM. If you go with a DI unit on bow, be sure and use the TM version of transducer with added shielding to help reduce chances of RFI.