Intellical™ ISENa381 is a digital, combination, sodium ion selective electrode (ISE) with a refillable double junction reference and built-in temperature sensor. The electrode measures sodium concentration in water samples. A 59 mL bottle of 0.02 M NH4Cl Electrode Filling Solution is included with the probe.The laboratory version of this ISE is shockproff with its Zeonor plastic body.The Intellical ISENa381 probe is available with a 1 or 3 meter cable and is intended for laboratory use. The ISENa381 is ideal for measuring sodium concentrations in wastewater, drinking water and general water quality applications.