I don't think PSA accepts items for graded contained in screw down holders. The thing I've noticed that I don't like about them is that for large formats say 1952-1956 Topps they tend to compress the cards and force them to buckle a bit once you screw down the holder. For smaller formats say 48 Bowmans or T206's they tend not to do that and I've found them to be fine.
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