HLI-2W2
The HelixNet HLI-2W2 is a dual 2-wire partyline interface module for the HMS-4X main station.

HLI-4W2
The HelixNet HLI-4W2 is a dual 4-wire interface module for the HMS-4X main station.

HLI-ET2
The HelixNet HLI-ET2 is a dual port Ethernet switch interface module for the HMS-4X main station.

HLI-FBS
The HelixNet HLI-FBS fiber linking interface is a dual port Ethernet switch interface module with 100MB SFP connectors for the HMS-4X main station. The HLI-FBS 100MB SFP connectors can be populated with compatible single or multi-mode fiber transceivers.