Features: 1. Hold function: Saves measurements for convenient readign and recording 2. Auto-off function: Turns off meter after 10 minutes of non-use to conserve batteries. 3. Measurement Range: 0-9999 ppm (When the measured value exceeds 999 ppm, please make the display value x10) Application: 1. Check the performance of your water filter. 2. Check for nardness (1 grain = 17ppm). 3. Make sure you always drink pure water! Please refer below standard for testing water 0-50 ppm --------- High Purity Water 50-100 ppm ------- Pure Water 100-300 ppm ------ General Pure Water 300-600 ppm ------ Fouling 600-1000 ppm ----- Poor Taste Water,Fouling Above 1000 ppm --- The water is not suitable for drinking Description: Condition: 100 % new and high quality! Item Type: TDS Water Meter Material: Plastic Measurement Range: 0-9999 ppm Accuracy: +/-2% Temperature Range: 0-50 celsius Size: 14x3cm/5.51x1.18" Package Includes: 1PC Water Purity Tester Tool Notes: 1 Please allow 1-3mm measuring deviation due to manual measurement. 2 Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Thank you!