Features: C-100 versatility of portable TDS / EC / SALT / S.G / TEMP water quality tester.  Mainly used for testing TDS (ppm /), EC (uS / cm, mS / cm), SALT (%), S.G (seawater gravity) and TEMP (ºC / ºF).  The pen type is simple and portable. Put the meter into the solution, it can quickly and steadily respond to the reading, and has a calibration function to ensure high accuracy.  The density of seawater in different regions is generally 1.02-1.07, and the weight of the dissolved salts is different about 3.5% on average. It is recommended to control the proportion of salt in this range.  Seawater salinity is the ratio of the total dissolved solids to the weight of seawater in seawater, usually expressed in grams per kilogram of seawater.   Specifications: Range: 0 to 10000uS / cm 10.01-19.99mS 20.1-400mS / CM;  Resolution: 1uS / cm; 0.1 ms / cm;  Accuracy: ± 2 ％ F.S;  TDS: Range: 0 to 1000ppm 1000ppm to 10000ppm 10.1 to 200.0ppt (auto out of range);  Resolution: 1ppm; 0.1 point;  Accuracy: ± 2 ％ F.S;  salinity: Range: 0.00 to 25.00%;  Resolution: 0.01%;  Accuracy: 0.01-5.00% (± 0.1%) 5.10-25.00% (± 1%);  SG: specific gravity of seawater 1.000-1.222;  calibration: EC: Three-point calibration is optional (1413uS 12.88mS 111.8mS);  Temperature compensation: ATC;  Operating environment: 0 to 80.0ºC (32.0-176F); <90%;  TDS coefficient: 0.5;  Temperature range: 0.1-80.0ºC 32.0-176ºF;  Temperature accuracy: + 0.5ºC;  Temperature resolution: 0.1ºC / ºF;  Automatic shutdown: 5 minutes;  Power: 3x1.5 LR44(Not Included);  Screen size: 28 * 17mm;  Size / weight: 159 * 34 * 16mm (6.31 * 1.3 * 0.6in) / 60g (2.1oz);  Display: support backlight;  Battery: Low battery indicator;   Package List: 1 * Water Tester;  1 * User Manual;   Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.