A card in a holder does look nice, and it is protected, but what is it protecting?
When the graders came into play after marketizing (my word) the numismatic hobby, their reason for doing so was uniformity of the grades given by the pre grading dealers of that time.
I luv comedy, and as it has turned out, we have NO uniformity among the grading groups, even within their own ranks.
They all know about corners, and sides, but when it comes to different card sets ... It's a crap shoot.
Folks, in the old days, if a dealer quoted you a grade that you didn't quite agree on ... you simply moved on to another dealer.
Now a days, the folks that aren't much into grading their own, will go by what the master of sides and corners will guesstimate the card to be.
We have found out that when a grader makes a mistake, it can be loud, and it could cost mucho coinage of the realm.
So if you don't know what the holder is protecting ... It could be expensive.
But I'll leave that to the Marketeers (my word)

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