Dual-Color Smart Backlight Water Quality Tester Pen 3-in-1 TDS Meter Conductivity & Temperature Detector 1. Purpose: Basis for detecting the replacement cycle of water purifier filter elements. To ensure clean drinking water. 2. 3-in-1 multi-function detection: TDS valueconductivitytemperature, switch modes by pressing the Mode button. 3. Accurate data, high-definition backlight, red light warning when TDS exceeds 40ppm. 4. Lock function: Automatic locking for easy reading and recording, the instrument will lock the reading. 5. Auto-shutdown function after 5 minutes of inactivity. Parameters: 1. Measurement range: --TDS: 0~9990 ppm, --Conductivity: 0-9990 uscm 2. Accuracy: +-2 percent 3. Green light on when TDS is less than 40ppm; red light on when TDS is greater than 40ppm. 4. Temperature range: 0-99 Celsius (32-212 Fahrenheit) 5. Battery: 1.5V x 2 button cells 6. Net weight: 53g 7. Dimensions: 15.5x3x1.5 cm