More description TDS Meter Digital Water r✔✔3-in-1 pH Meter: water quality r has a three-in-one function, which can measure PH, TDS and temperature with high precision. All-round measurement of water quality to ensure healthy water quality. The water ph meter is an ideal gift for family and friends. ✔✔Due to Recently Reviews about 1413 Solution, please note that TDS Meter had been calibrated by 1413 solution in advance; You can use it directly and it could last for 1 year without second calibration; So 1413 calibraiton solution is not included ✔✔PH Meter for Food with Safety Perforation Design The Portable tds water r compact design can be carried around, and the safety perforated design on the top can also save space when hung. ✔✔PH r Water with Full Waterproof Design IP67 Fully waterproof rubber ring design, IP67 waterproof level, each part of the product will have a sealing ring. ✔✔Digital Ph Meter with Built-in Buoyancy After ph meter for water 0.01 digital ph enters the water, it will immediately rise for easy salvage. ✔✔PH Meter for Water Hydroponics with Ceramic Temperature Electrode- Extremely fast and accurate measurement of liquid temperature, automatic calculation of temperature compensation. ✔✔[Calibration PH steps of PH Meter Digital Water Quality r]: Step 1: Press the ON button to turn on Step 2: Press the TEMP / CAL button Step 3: Adjust to pH mode Step 4: Place the electrode in the pH 4.00/ 6.86/ 9.18 standard solution Step 5: Wait for the readings to stabilize(usually 5~10 Seconds) Step 6: Press and hold the TEMP/CAL button for 6 seconds, then you can see corresponding value flashing 3 times which means calibration of pH is completed.