It is the black webbing on the backside of the leather, the lighter grey feels like very rough leather which I don't think I would use. I have been looking at videos on how to refresh and I have seen what appears to be the webbing that I have taken a picture of.

I have been thinking of ordering either the chromium oxide crayons or diamond spray, what should I go with?

Appreciate your help... Robert

https://www.dropbox.com/s/ht3y83lw47...Strop.JPG?dl=0