In the Infamy 3.3 update, OVERKILL added this fancy new functionality for "detail normal maps" that basically repeat a really small normal map, tiling it onto the model. It's supposed to add detail like making fabric appear stronger.
That's actually a pretty cool feature, but I don't like it very much on the Discerning Dandy in particular since I think it makes it look a little too crusty.
This mod just makes the detail normal maps blank, which makes the outfit look smoother. The regular normal map is still intact.