The datasheet for the N25D says that the NT1 tip is suited for the N25D.
Looking at the image of the tip, it in no way resembles that presently in either of my N25Ds.
The first one that I bought has a screw plate holding the pencil in, the second has a nut. On top of that, the first one is a threaded barrel for the tip, whilst the other has a philips screw holding the tip in place.
Neither of these resemble that description, nor the tech drawings for the NT1 which appears to be a complete set - both the pencil and the tip.
The iron's datasheet:
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The tip's datasheet:
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