Thanks for this information. I just looked at Hanna's web site and, as you say, they state a +/-4% accuracy. I've had my two sample cuvettes of syrup and the calibration cuvette sitting upright in a closed cupboard since July 10th and just took them out now for a series of measurements being careful to handle them just by the plastic caps not touching the glass etc. Sometimes the measurements are repetitive and sometimes they are +/- 4% i.e. one reading at 48% transmittance the next, seconds later, at 50%. I suppose these results are better than just eyeballing the syrup but I find them disappointingly inaccurate.