From what I reckon, the grey one is superior in terms that since it is glass and not plastic, it is clearer and more scratch resistant. However, the plastic one has a bigger viewable area and slightly higher magnification factor , at the expense of it getting scratched very easily and having a much more cloudy view of the magnified object. All in all , the consensus is that in spite its shortcoming, the grey one is superior for most uses.Also one question, are there different versions/iterations of both the grey and trasnparent one? Or are there variations per era/date of manufacture?
The old grey one has a glass lens (8x), then there was a plastic one (5x) and the latest iteration is a glass lens (6x) in a plastic housing
Three versions of the gray housing one? May I ask what era o what year was the cutoff for each version? Also, how to distinguish between the three versions if I were to buy it in an online auction?