Sensitivity and fit
The 61F-GP-N8H AC120: The 15kOhm to 70kOhm sensitivity adjustment means this unit can be tuned for the specific conductivity of the process liquid — from relatively pure water (higher resistance) to more conductive solutions (lower resistance). If your liquid's resistance falls outside that band, the relay won't switch reliably. The SPDT (2 Form C) contact gives both normally-open and normally-closed outputs, so you can wire either fill or empty control from the same block.
Mounting is socketable via an 8-pin octal base — common footprint, easy to swap without rewiring the panel. Termination is plug-in, so the controller body pulls straight off the base for replacement or bench testing.