Includes:

1 FULL bottle of pH-4 (14 ml) calibration value 4.01 ±0.02 pH @ 25°C - model 514-4

1 FULL bottle of pH-7 (14 ml) calibration value 7.00 ±0.02 pH @ 25°C - model 514-7

These are the original calibration standards included with the meters LAQUAtwin pH-11/22/33