Slim, ergonomic design with rounded edges and a case that is only 17 mm (0.7 inch) thick, the HI98107 is thin and fits comfortably in the hand or pocket Large Multi Level LCD: The LCD is 29 mm (1.125 inch) x 20 mm (0.81 inch) allowing the user to easily read both the pH and temperature simultaneously Two-Button Operation: One for on or off, the other for calibration Integrated Temperature Sensor: Built in temperature sensor allows for temperature compensated measurements Temperature can be displayed in either degree Celsius or degree Fahrenheit pH range 0.0 to 14.0 pH pH resolution 0.1 pH pH accuracy ±0.1 pH Temperature Range: 0.0 to 50.0 degree Celsius or 32.0 to 122.0 degree Fahrenheit Temperature Resolution: 0.1 degree Celsius or 0.1 degree Fahrenheit Temperature Accuracy: ±0.5 degree Celsius or ±1 degree Fahrenheit pH calibration automatic, one or two points Temperature compensation automatic from 0 to 50 degree Celsius (32 to 122 degree Fahrenheit) Auto-off after 8 minutes, 60 minutes, disabled Environment 0 to 50 degree Celsius (32 to 122 degree Fahrenheit) RH max 100 percent Automatic Calibration: Automatic calibration to one or two points using standard buffers (pH 4.01, 7.01 and 10.01) Stability Indicator: A clock tag stability indicator will disappear to alert the user when the reading is stable Automatic shut-off, user-selectable time until meter shuts off to conserve battery life Options are 8 min, 60 min or disabled Low Battery Indicator: Low battery indicator that is displayed when less than 10 percent battery life is remaining Low Battery Indicator: Low battery indicator that is displayed when less than 10 percent battery life is remaining Range: 0.00-14.00pH Resolution: 0.1pH Accuracy: ±0.1PH or 0.05pH Power: 4 x 1.5V (LR44/button cell) Calibration: Manual, 2 points Auto shut-off: Approx. 4minutes Dimension: 17.5 x 4.1 x 2.3 cm Net Weight: 90g OPERATION • Remove the protective cap. Do not be worry if white crystals appear around the probe head. This is normal with pH electrodes and they dissolve when rinsed with water. • Turn the meter on by sliding switch on the top. • Immerse into solution up to the max immersion level. • Stir gently and wait until the display stabilizes. • After use, switch off pH meter, use the water clean the electrode and replace the protective cap. • Large fluctuations in readings could be due to lack of calibration, dry electrode or rundown batteries. CALIBRATION • Immerse the tester up to the maximum immersion level in pH 6.86 buffer solution • Allow the reading to stabilize and using a small screwdriver adjust the calibration trimmer to read 6.86 Calibration is now complete. ALWAYS USE FRESH BUFFERS FOR CALIBRATION. BATTERY REPLACEMENT When the meter cannot be switched on or the display fades, pull out the battery compartment and replace all 4* 1.5V batteries, while paying attention to their polarity. Batteries should only be replaced in a safe area using the battery type specified in instruction manual. (1.5 Alkaline or AG13).