HI 8633 and HI 8733 have been designed specifically for use in areas of production and quality control. It is often necessary to test samples with different concentrations ranging from deionized water to brine. The amperometric system would require constant recalibration and probe changes, thus making the measurement process very time consuming and unreliable. To solve this problem, HANNA has developed the HI 8633, which uses a 4-ring potentiometric probe. The rugged probe is made of PVC - ideal for indoor, as well as outdoor measurements. By using one point calibration, it is now possible to obtain accurate readings across a very wide range, from 0.1 to 199900 µS/cm. If temperature of the solution fluctuates, HI 8733, with a built-in temperature sensor and Automatic Temperature Compensation, is the perfect instrument. As an accessory, the HI 721313 is available. The kit includes a rugged carrying case with a beaker, a calibration screwdriver and standardizing solution at 12880 µS/cm.