PH Calibration Buffer Solution Kit 18 Packets 6.86 4.00 9.18 for Digital Meter Tester Pen Suitable with most of pH meters, perfect Calibrating.<br> pH buffer calibration solution powder accuracy is 0.01pH, accurate and precise.<br> Individually wrapped to maintain freshness until use. Made with qualify materia.<br> 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.<br> 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.<br> Color: As shown<br> Material: Plastic<br> type: 6.86/4.01/9.18<br> Package Contents:<br> 18*pH buffer<br> Only the above package content, other products are not included.<br> 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.