These packages are used to make a buffer solution to calibrate your pH pen. Simply mix them in water, dip in your pH pen, and make your adjustments.
Once you make a solution it can be reused 10 times before you need to throw it out. You can keep this solution in a small mason jar and store it in a cool dark place.
When you order, you will receive 5 of the pH 4 buffer solution packs, and 5 of the pH 6.86 packs.