Digital pH Meter Tester Pen for Water, Pre-Calibrated, High Accuracy ±0.01, 0�

【Calibration Operation Guide】 Press and hold the CAL button for 5 seconds to access calibration mode. Complete calibration by selecting the standard powders in this exact order: 6.86 → 4 → 9.18. Please refer to our full calibration instructions and tutorial video for detailed steps. 【Pre-Calibrated for Immediate Use】The pH meter is pre-calibrated before shipment and can be used directly out of the box. For best accuracy, readings may vary slightly depending on water conditions and environment. 【Easy Operation】Simply turn on the device, immerse the probe into the solution, gently stir, and wait for the reading to stabilize before recording the result. 【Compact & Portable Design】Pocket-size design allows easy carrying for testing anytime, anywhere. Suitable for home, travel, and outdoor use. 【Multi-Purpose Water Testing】Ideal for drinking water, swimming pools, aquariums, hydroponics, RO systems, and other environments requiring pH monitoring.