The Myron L Company FCE function reports FAC quickly and accurately by measuring ORP, the chemical characteristic of chlorine that directly reflects its effectivity, cross referenced with pH. Both DPD kits and colorimeters may tell the user the FAC value of the sample in the test tube, but since the chemistry of that sample is quite different from the source water being analyzed, the results are imprecisely related to actual disinfection power. The Myron L Company FCE function measures the real, unaltered chemistry of source water, including moment-to-moment changes in that chemistry. Accuracy of BETTER than ?1% of reading Autoranging Conductivity/TDS Superior resolution 4 Digit LCD displays full 9999 ?S/ppm Real Time Clock with Date and Time Data Logging with Date and Time stamped in memory Waterproof to 1 meter/3 feet pH Calibration Prompts Low battery indicator User adjustable timeout "Auto-off " All Sensors are internal for maximum protection Download capability with optional uDock Display 4 Digit Liquid Crystal Display Dimensions: LxWxH 196 x 68 x 64 mm/ 7.7 x 2.7 x 2.5 in. Weight 352 g/12.4 oz. Case/conductivity cell material VALOX* Cell capacities pH/ORP: 1,2 ml/0.04 oz. Cond/TDS/MIN/SALT: 5 ml/0.2 oz. Power 9V alkaline battery Battery life 100 hours (5000 readings) Operating/storage temperature 0 ? 55?C/32 ? 132?F Protection ratings IP67/NEMA 6 Waterproof to 1 meter/3 feet