The product description does not mention that a gram balance must be used to prepare the calibration solution. The % scale on it does not reach 0%, which means that distilled water cannot be measured. This significantly increases the price of the product (if you don't already have a scale), not to mention increasing the time spent on the multi-step, multi-tool calibration process. To be fair, I think you could use olive oil to calibrate a refractometer, but olive oil can vary by as much as a percentage point and that can quickly tell the difference between grade A/B honey and grade C honey. You may want to look into another refractometer, or at least be aware that this one is not as easy to use as described.
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