Ensure accurate results from your electronic ORP testing equipment with individually-sealed, single-use calibration solutions. Each sealed packet of ORP/REDOX 400mV Calibration Fluid contains approximately 20mL of standardized calibration solution - just the right amount to allow proper calibration with minimal waste. ORP/REDOX 400mV Calibration Fluid is a high precision calibration solution with a standardized ORP value of +400mV with ±2mV accuracy. Use as needed to confirm the condition and accuracy of your electronic ORP probe. Once your ORP probe is calibrated, experience extremely precise measurement of aquarium ORP values! 4 pack.

HYDROS ORP/Redox 400mV Calibration Fluid Directions
Tear open top. Immerse probe tip into solution. After reading stabilizes, adjust display on the meter to match the calibration fluid of +400mV. Please note: Solution is highly accurate for a maximum of 60 to 90 minutes exposure to air. Do not reuse solutions. Do no store ORP/REDOX probe in this calibration fluid.