Many thanks Leonard - quite straightforward really. I was thrown by the 0.75 (thread pitch), can't see why anyone would bother to state that, especially if they are all the same.
There are a very few larger-diameter lenses which have "coarse" filter threads with a pitch larger than 0.75. The Tiffen (Mfr# 105CCLRUN) 105mm Coarse Thread Clear Uncoated Filter is larger, for example.
I think the reference is just caution.
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