The 360 comes with the AS GPS HS antenna. It has a compass (Heading Sensor). The reason it comes with that antenna is to create waypoints on the 360 view.
You don't have to use it, but the GPS function will be more stable with it.
You need an adapter cable for the connection----- AS GPS NMEA
Humminbird Helix 12 SI, 1198c SI, 1198c SI, ONIX 10 SI NT, 360, RC-1