Humboldt HM-4160 FlexPanels - Manual (Page 14)

Connecting Utilities
Located on the back of each FlexPanel is one or two service connector plates.
These connector plates are used to connect utilities to the panels (Figure 7).
Twenty feet of 1/4-inch plastic tube has been supplied for service connections.
Figure 7
Rear of Control Panels (HM-4140, HM-4150, HM-4160) showing
Lower and Upper Service Connector Plates. Also shows plugs
used in exit connector for Pressure and Readout when not using
Add-On Panel.
Rear of Add-On Panels (HM-4150A, HM-4160A) showing Lower
Service Connector Plate.