PH Calibration:1.lmmerse the electrode in pH 6.86(pH7.00)standard buffer solution of phosphate,and gently shake it.2.Allow the reading to stabilize and with a small screwdriver turn the calibration trimmer until the display shows 6.86(7.00).Rinse the electrode with distilled water,and suck it with filter paper.3.lmmerse the electrode in a PH4.01 or PH 9.18 buffer solution,gently shake the electrode and waiting for the reading to stabilize.The showing value and buffer solutions ph value is within error range.4.The calitbration of the instruments pH range is now complete.Model:ph-61181Measuring range: 0.00~14.00pHAccuracy : +/- 0.2PH +/- 0.1PHResolution: 0.01PH Operating Temperature : 0C~50C Automatic Temperature Compensation : 0C~50C Automatic Temperature Compensation : 0C~50C Electrode:For cheese milk testingPower Supply:3*1.5V(AG13) (Not inculde)Colour: blueMaterial: ABSPackage Contents:1 * PH-61181 Meter1 * English Manual1 * ScrewdriverOnly the above package content, other products are not included.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.