Immerse yourself in the world of precise water analysis with the pH4 calibration solution set from FSRTOP. This high-quality test kit is essential for accurately determining the pH of your aquarium or pond water and is ideal for all types of water. Manufactured in Germany, the pH4 calibration solution guarantees reliable and precise determination of the optimal pH values in order to always keep the living conditions of your aquatic inhabitants in balance. pH 4 calibration solution calibration liquid buffer solution calibration solution for pH measuring device tester calibration liquid Can be used immediately, no stirring/mixing necessary Long shelf life, batch certificate available upon request very precise - at the specified temperature the pH value deviates from the specified value by