Use of PH Meter Buffer Solutions: 250 ml of buffer solution can be used several times, the used buffer should be poured out and not reused. The remainder should be stored in a cool dry place at 20-25 and sealed. After using it for a period of time, the electrode of the ph meter be asymmetric, and the potential undergo significant changes, so regular calibration is necessary. Name:PH Meter Buffer Configuration Kit Power Supply:2xAAA batteries (1.5V) Not Included Battery. Cleaning method for buffer preparation device: After use, put clean water into the mixer and stir that can be repeated multiple times, or simply rinse the mixer. All containers that have come into contact with the standard solution should be rinsed clean with clean water multiple times. Color:As Shown Material:plastic Package Contents: 1 * PH Meter Buffer Configuration Kit Only the above package content, other products are not included. Note: Light reflection 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.