These Garmin fishfinders have CHIRP sounder circuitry built into the display itself so that a CHIRP transducer can be plugged directly into the display and no external sounder box is needed.
Garmin offers other displays not shown here which need an external sounder box connected through a Garmin Marine Network high-speed cable to be able to handle CHIRP transducers.
See Garmin's Fishfinder page for more information.