The HM Digital HMDCOM80 HydroTester is a great tool for your hydroponics and gardening. The meter measures electrical conductivity (EC), total dissolved solids (TDS), and is also excellent for nutrient testing. This hydrotester features automatic temperature compensation and is water resistant. The HM Digital hydrotester has a large easy-to-read display that also displays simultaneous temperature readings, allowing you to easily monitor and adjust your measurements. Comes with a one-year warranty and one 3V button cell battery.