4-in-1 Water Test Kit: Includes a 3-in-1 pH meter and TDS meter. Displays important water parameters such as pH, TDS, electrical conductivity (EC), and temperature in just 5 seconds. No more tedious comparisons with test strips. Accurate Measurement: The pH measurement range is 0.00 to 14.00, with an accuracy of ±0.05 pH. The conductivity meter measures EC values from 0 to 9990 µs/cm and 0 to 9990 ppm, with a display accuracy of ±2% for TDS and conductivity. The conductivity meters have two display units: °C and °F. Simple and Consistent Accuracy: The manufacturer has calibrated the water quality pen (the white tip on the pH meter probe is the residue of the calibration liquid remaining on the probe after calibration. It will disappear after rinsing with clean water and does not affect use). The digital pH meter uses a one-point or three-point calibration method (pH 4.00, 6.86, and 9.18) for accurate calibration. Versatility: Ideal for analyzing drinking water, aquariums, swimming pools, ponds, etc. Compact size for measurement at home and on the go. User-friendly design: The LCD screen on the aquarium thermometer is easy to read. Automatic shutdown saves battery life. Convenient size and easy to use.