TDS-EZ Water Quality TDS Tester, 0-9990ppm Measurement Range, 1ppm Resolution, Accuracy of /-3% of Reading Ideal budget model for end users. High efficiency and accuracy with its advanced microprocessor technology.Hold function: Holds measurements for convenient reading and recording and battery life is approximately 1000 hours of battery life. Usage & Power Source: 2 x 1.5V button cell batteries (included) (LR44 or equivalent)Auto-off feature: meter automatically shuts off after 10 minutes of non-use for save batteries. Display: Large, easy-to-read LCD display.Measurement range: 0-9990ppm. From 0 to 999ppm, the resolution is in 1ppm increments. From 1000 to 9990 ppm, the resolution is in 10 ppm increments, indicated by a flashing x10 image. Very strong and durable translucent blue housing.TDS-EZ meters are calibrated with 342 ppm NaCL solution. Meters can be recalibrated with a mini screwdriver. Includes a TDS sticker on the back of the meter that explains TDS values.