PINPOINT High-Precision pH Calibration Fluids Kit contains 20 packets: 10 pouches of 4.000 +/- 0.002, 10 pouches of 7.000 +/- 0.002 Calibration Fluids. Each one comes in it's own plastic envelope packet. They are ready to use, no mixing required, are extremely accurate and field portable. Each packet contains ample fluid for calibration (about 25 ml).