Eight materials on the lid side
On this page11
The closure material list on this shelf is unusually long
185 polypropylene, 30 metal, 5 urea, 4 PET, 3 recorded as plastic and metal, 2 recorded simply as plastic, 2 HDPE and one recorded as metal and polypropylene.
Which is eight values against three on the container side
And two of the eight are composite values rather than single materials. Plastic and metal, and metal and polypropylene, describe a part made of two things rather than a choice between them.
A composite value is a different kind of entry from a single one
It cannot be filtered the same way. A search for metal closures that matches only the exact string metal returns 30 rows and silently drops the four that are partly metal.
And two rows are recorded simply as plastic
Which is a category rather than a material. A row reading plastic is telling a buyer less than a row reading polypropylene, and the two sit in the same column as though they were the same kind of answer.
So the eight values are not eight comparable options
Four are specific polymers, one is metal, one is a thermoset, two are composites and one is a category. A count of distinct values overstates how much choice the column describes.
That is the same observation the automotive property makes from a different angle
There, a field that was complete on every row turned out to restate the material. Here a field with eight values turns out to mix four kinds of answer. Both are about what a column can actually distinguish.
The polypropylene majority is the practical fact
185 of 232. So four closures in five are the same material, and the remaining 47 rows carry all the variety.
Metal is the largest of those and it has a real consequence
A metal cap on a plastic jar brings a different thermal behavior and a different feel, and on this shelf it is the only way to get a metal part at all.
And urea at five rows is the clearest example of a tail entry
A thermoset used where polypropylene is too soft or too heat sensitive. Five rows out of 232, which is the kind of option a buyer only finds by enumerating the column rather than by filtering it.
Which is the argument for enumerating a field to the end
The trains and dioramas property found a contradictory row that way, by counting families to the end rather than taking the top of a list. Five urea closures were found the same way here.