Model: TDS-139A - Color: Blue - ABS material housing - 1.0" LCD display - Measuring range: 0 ~ 1999 ppm (mg/L) - Resolution: 1 ppm (mg/L) - Datum temperature: 25'C - Accuracy: +/- 2% / 'C - IP88 waterproof - TDS is an expression of mobile charged ions (such as minerals salts metals cations and anions) dissolved in particular amount of water - Commonly used unit in TDS is milligrams per liter (mg/L) or parts per million (ppm) - Has a wide range of applications including aquarium hydroponics hardness of water laboratories water systems pools and spas - Powered by 4 x AG13 batteries (included) - Comes with a wrench and English user manual