Whatever y cable they sell that connects mega 360 to helix to split sonars. I haven’t bought the mega 360 or the splitter yet. I have the HW dual spectrum chirp 2d puck already. Will connect to a helix gen3 12 mega+si. I have zero desire for a mega transducer on my trolling motor and this will likely be my only bow unit for the time being until I see live and more details