There is an issue emerging with respect to some purportedly leather materials applied to R/P outer soles.
The precise nature of the materials is not clear. However, it appears to be VERY thin leather that has the appearance of paint applied to the outer sole.  The NIS has referred the matter to the Headquarters Office. Members who import footwear with this application should be aware of the possibility that CBP will reject the material as consisting of either leather or composition leather.