My Hach HQ40D doesn't recognise my new ORP probe? - The Laboratory People
HACH HQ40d Portable pH, Conductivity, Dissolved Oxygen, ORP, and ISE Multi-Parameter Meter | EMIN.ASIA
HQ40D Portable pH and Conductivity Meter, Laboratory Kit for Water Quality, with Refill pH Electrode and 4 Poles Graphite Conductivity Cell, 1 m Cable | Hach - Overview - Obsolete