One of the most frustrating aspects of collecting early 80's twin fins is trying to find original Star Fin fins for twin fins. This system was particularly popular in the US. I have found 2 solutions recently. The first is a plastic fin box converter made by FCS for long board center fin boxes. These work well in the Star Fin fin boxes and take the FCS Mark Richards template fins beautifully. The second solution is a guy in Florida who is making fantastic replicas. Who can contact him via the Bruce Jones surf surf in Seal Beach California.