1 calibration point, easy to use and very precise<br> Measurement of oxidation-reduction potential (ORP) of water<br> Manual Calibration with screwdriver (included)<br> Measuring range: -1999 mV 1999 mV<br> Calibrate with 256mV buffer solution (not included in the set)<br> Carry design everywhere<br> Resolution: 1mV<br> Accuracy: 5mV<br> Automatic Temperature Compensation (ATC): 0-50 C<br> Calibration: 1 point<br> Battery life: more than 1000 hours<br> Size: 31x155x16mm<br> Weight: 60g<br> Material:plastic<br> colour:Green + blue<br> Package Contents:<br> 1 * ORP Meter<br> 1 * Mini Screwdriver<br> 4 * 1.5V AG13 button battery<br> 1 * English User Manual<br> Only the above package content, other products are not included.<br> Note: Light 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.