Fangrui Product Details Please Note: The Physical Slightly Color Difference Or Difference, Does Not Affect The Use, Please Do Not Mind, Thank You! [ Lcd Backlight ] : Our Tds Water Meter Is Equipped With Low-power Backlight Technology, Which Makes It Easy To Test Water At Night Or In Dark Places. It Can Also Be Used To Distinguish Drinking Water From Non-potable Water. The Red Backlight (ppm 40) Reminds Users That The Current Water Quality Is Not Ideal, Indicating That It Is Not Potable. [3-in-1 Test Function]: With The Advanced 3-in-1 (tds, Ec, Temperature) Conductive Pen, The Tester Can Not Only Detect Tds, But Also Ec And Temperature In The Water. The Ppm Meter Ranges From 0-9990 Ppm, And The Temperature Also Supports Two Reading Modes: Celsius And Fahrenheit. Simple And Easy To Operate: Simply Turn On The Tds Meter, Gently Stir The Water, And Within Seconds The Lcd Display Automatically Lock, And The Tds Meter Automatically Turn Off After 2 Minutes Of Inactivity To Conserve Batteries. Instructions For Use: 1. Remove The Pe