Product Description: High quality at an affordable price. Used for detecting Total Dissolved Solids (TDS)/NaCl content in freshwater aquariums, ponds, and water purification systems. The smart pen integrates TDS, conductivity (EC), and thermometer functions for improved measurement accuracy. Features automatic temperature compensation, with a measurement range of 0-9999 ppm +/- 2%. Four display modes: The SHIFT button switches between TDS (ppm/°C), EC (s/cm/°C), TDS (ppm/°F), and EC (s/cm/°F). A lock function facilitates reading and recording; press the HOLD button and then remove the pen from the test solution. The instrument automatically shuts off after 5 minutes of inactivity. Conductivity: 0 - 9999 s/cm Total Dissolved Solids (TDS): 0 - 9999 ppm Temperature Range: 0.1 - 80.0°C / 32.0 - 176.0°F Resolution: TDS: 1 ppm; EC: 1 s/cm Battery: 1 x 3.0V (CR2032) Accuracy: 2% Color: White Material: Plastic Dimensions: 152 x 30 x 14 mm Package Contents: 1 x TDS/EC Tester Includes only the above package contents; other products are not included. Note: Light and different monitors may cause slight color differences between the actual product and the picture. Measurement error is +/- 1-3 cm.