Suitable with most of pH meters, perfect Calibrating.pH buffer calibration solution powder accuracy is 0.01pH, accurate and precise.Individually wrapped to maintain freshness until use. Made with qualify materia.Easy to use: Mix the buffer powder with 250ML distilled water, put the pH meter in the solution and gently stir and wait a few seconds for the result.18 pack ph calibration packets: 6*ph 6.86 packets, 6*ph 4.00 packets, 6*ph 9.18 packets, cost-effective and flexible for using.Color: As shownMaterial: Plastictype: 6.86/4.01/9.18Package Contents:18*pH bufferOnly 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.