I use various shaving creams that come in a tube and several of them have an “e” on the line of text that shows the weight/volume of the contents. Usually looks like
5.6 oz. e 158.8g
It’s a stylized font and usually looks the same, like it is some standard. Here are some examples
It represents an estimated measure of weight or volume, as required by European labeling regulations. Estimated sign - Wikipedia
It means ‘estimated’ - that is, they calibrate the machine to fill to a certain level, then let it run, assuming that it’s doing a good job, perhaps further confirmed by random sampling, but not weighing each and every filled package.
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