If the 858 is the HD model it will Ethernet to ONIX for Waypoints only ...
If the 858 is the HD model it will Ethernet to HELIX for Waypoints, Accessories, and xducers with "like" Sonar technologies ...
If the 858 is the HD model it will Ethernet to iLink ...
Is the 858 the Sonar model or the DI model ...??
Rickie