Go to J&P Cycles in Anomosa web site.
I have one of their rubber ones.
Work good for me, also keeps a lot of nail, screws and pieces of old pliers from getting stuck in my rear tire.
I'm trying to find a picture of the bike with the flap on in a good view.

Best I could do.
http://www.jpcycles.com/product/7110315This is a close one in size and etc.