HydroMaster Digital tester makes monitoring water easier than ever by reading the levels that matter most and providing accurate readings that you can depend on. Continuous pH/EC/TDS/Temp monitor with rechargeable battery. Portable, wall mount or benchtop use. Tests pH at a range of 0 pH-14 pH, temperatures from 30°F-176°F, TDS from 0-9999 ppm and EC from 0-9999 μS. Stores up to 20 measurement readings, so you can monitor changes over time. LCD touch-type screen with auto backlighting.