tds tester/ph tester/ec tester/orp tester USE THE TDS METER TO: *Check the performance of your water filter*Check for hardness(1 grain=17ppm ... :Measures from 0-999ppm, with a resolution of 1ppm. From 1,000 to 9,990ppm,the resolution is 10ppm,indicated by ... (Button Cell)Size: 14.2 x2.5 x1.5cmWeight:36g(1.27oz)Auto shut-offData holdAuto Temperature compenstion1000+ hours of continuous ...