This is the official replacement pH probe for your Grobo.
Unfortunately pH Probes do not last forever as they age through normal use and will eventually fail. With good care and use (keeping the probe tip wet and cleaning once a month) you will extend its life. This pH Probe has a Double Junction Reference which provides a longer life than many other pH probes and is a gel filled non-refillable probe, so apart from cleaning it is maintenance free.
We recommend purchasing a calibration kit as well to calibrate the probe once it has been installed.