100% new with high quality and good price. For checking TDS/salt (NaCl) levels freshwater aquariums, ponds and water purification systems. smart pen combines TDS, EC, and a temperature meter for improved accuracy. With an Automatic Temperature Compensation and the measuring range of 0-9999 ppm +/- 2%. 4 Display modes: SHIFT button: TDS - ppm & Celsius, EC - s/cm & Celsius, TDS - ppm & Fahrenheit, EC - s/cm & Fahrenheit. Lock function, easy to read and record, HOLD button then remove from test solution. The instrument automatically shut down after 5 min of inactivity. Conductivity: 0 - 9999s/cm TDS: 0 - 9999ppm Degrees Celsius: 0.1 - 80.0 Celsius Fahrenheit: 32.0 - 176.0 Fahrenheit Resolution: TDS: 1ppm; EC: 1s/cm Battery: 1x3.0V (CR2032) Accuracy: 2% Colour:White Material:plastic Size:152 x 30 x 14mm Package Contents: 1 x TDS & EC Meter Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.