Dong-A DKK's portable PH meter was used but failed. Purchase this product looking for alternatives. I am thankful that I bought two of these at a price of one PH meter made by Toa DKK and that fishing came. Sensitivity was a little dull, I felt it was easier to use than the PH meter of Donga DKK if it was used exclusively for PH measurement. The calibration of PH was also easy. However, it is troublesome to set the temperature correction each time, so it is set at the average water temperature. In the case of strict measurement, there is a temperature correction probe. As the sensor seems to be poor and fragile, PH pH standard solution (4.00 7.00) and sensors should be posted on the site as soon as possible.