Networking 2 helixs

I have 2 gen1 helix 9s that i want to share waypoints with. What all do i need because i cant find this magical wire that people say plugs directly from 1 unit to the other. From what im getting i need 2 connectors 2 wires and a ethernet box.

For just two units and no other Ethernet connections:

Two each---AS EC QDE Ethernet adapters--one for each unit to connect the Ethernet cable to them.
One each---Ethernet cable--AS EC 20E is the 20' version, there are other lengths.