Calfskin. I actually really wanted the alden shells, but i tried on both last week and the two shoes, to the naked eye, are totally indistinguishable. I guess over the years there will be some difference in performance, but at literally half the price these seem good to me. That said, I think they're probably the nicest shoes I've ever bought, my previous purchases all being more than 5 years old and typical banana republic stuff. So, some advice, please, from those of you who know better. Should I add a waterproofing polish/cream/whatever to these immediately once I decide they fit perfectly, before polishing them and/or wearing them outside? Or is it bad for the shoes to add that stuff to your shoes?