[Large Display and Green Backlight] This PH EC TDS Temp meter has large display and green backlit which can read the pH TDS EC meter at different angles and low light. Press the HOLD/TEMP key to lock the reading convenient for recording data. ;) [Automatic Calibrate PH] This meter can automatically calibrate the pH value which supports 6.86 4.01 9.18 three-point pH value calibration. It has pH meter calibration powder to meet your calibration needs (EC and TDS meters are pre-calibrated). ;) [Multipurpose] This test meter is suitable for DWC hydroponic systems RO/DI water drinking water tap water beer milk wine kombu tea aquariums hot tubs swimming pools aquaculture and more. It can help you know whether water is in the optimal range. ;) [Stable Reading] This meter has stable PH reading with additional chip. It can reduce the interference of mobile phones and other items on the instrument. The automatic temperature compensation (32-122 ) keeps the reading consistent. ;) [4 in 1 Digital Meter] This test meter can measure pH value EC value (conductivity) TDS (total dissolved solids) and PH change during the hydroponics process. Just press the MODE/CAL key and switch the readings of pH EC (S/cm/ mS/cm) TDS (ppm). ;)