Sper Scientific water quality bench top meter from Sper Scientific measure all of the following parameters: pH, ORP (oxygen reduction potential), mV, conductivity, TDS (total dissolved solids), salinity and temperature. Features rugged housing with large LCD displaying the parameter being measured together with time, date and temperature (in C or F). Operates on AC voltage (no batteries). Comes ready to use with conductivity electrode (also measures TDS and salinity), pH electrode (also measures mV), multiple electrodes holder arm, AC adaptor, computer cable and software. Also accepts any pH or ORP probe with a standard BNC connector. Measures 8-1/2-inches length by 6-1/2-inches width by 2-1/4-inches height. Grade level: middle-high school. No allergens. No choke hazard. pH: 0 to 14 range, 0.01 resolution, +/- 0.02 accuracy. MV/ORP: -1999 to +1999 range, 0.1mv resolution (-199.9 to +199.9 otherwise 1mv), +/-0.2mv accuracy (-199.9 to +199.9 otherwise +/-2mv). Conductivity: 0 to 19.9 uS/cm range, 0.01 resolution, +/-1 percent fs + 1d accuracy; 0 to 199.9 uS/cm range, 0.1 resolution, +/-1 percent fs + 1d accuracy; 0 to 1999 uS/cm range, 1 resolution, +/-1 percent fs + 1d accuracy; 0 to 19.99 mS/cm range, 0.01 resolution, +/-1 percent fs + 1d accuracy; 0 to 199.9 mS/cm range, 0.1 resolution, +/-1 percent fs + 1d accuracy. TDS: 0 to 19.99 ppm range, 0.01 resolution, +/-1 percent fs + 1d accuracy; 0 to 199.9 ppm range, 0.1 resolution, +/-1 percent fs + 1d accuracy; 0 to 1999 ppm range, 1 resolution, +/-1 percent fs + 1d accuracy; 0 to 19.99 ppt range, 0.01 resolution, +/-1 percent fs + 1d accuracy; 0 to 199.9 ppt range, 0.1 resolution, +/-1 percent fs + 1d accuracy. Salinity: 0 to 11.38 ppt range, 0.01 resolution, 1 percent fs+1digit accuracy; 0 to 80 ppt range, 0.1 resolution, 1 percent fs+1digit accuracy. 23 to 176 degree F range, 0.1 resolution, +/- 0.9 degree F accuracy. -5 to 80 degree C range, 0.1 resolution, +/- 0.5 degree C accuracy. CE Approved.