Features: 5x 4.01 solution (potassium hydrogen phthalate) 5x 6.86 solution (mixed phosphate) 5x 9.18 solution Description: 1. No need to measure, just mix each packs with 250mL distilled water. 2.The set includes 5 package of 4.01, 5 package of 6.86 and 5 package of 9.18 calibration solution powder for all pH needs. 3.Designed for portability.Individual sized packets can be tucked in drawer, bag or suitcase for travel. 4.Save time and money.By mixing powders in a jar of distilled water, this lets you keep them longer and more readily available without needing more packets. 5.Wide range of applications.Great for testing pH balance of drinking water, pool, aquarium, RO system, Spa, or hydroponics. Directions for use: Step 1:Completely empty the powder into a clean 250mL glass beaker. Step 2:Add 250mL deionized water (or distilled water) to the beaker. Step 3:Stir until the powder has completely dissolved. Step 4:Follow the Esee pH meter calibration steps to calibrate your pH meter(Asin for Esee PH meter: B01LWMJVPG ) includes:15x PH Calibration Powder