Jeff, Chuck, and all interested partys. Here is dialog from a recent inquiry on the TZ Sinn forum.

dalstott - Is this a Sinn or a sinful fake?
Chuck Maddox sent me this picture of what appears to be an Excel O Graph with a Sinn label. We are aware of the two legitimate variants from Elka and Excelsior Park that are pictured.
Can this be a Sinn version or just a fake?

Michael Sandler
- I will ask the company directly for you [nt]

Response from Sinn - That's a very old version of model 903 with blue dial. Movement Excelsior Park 40-68. A rare model. Production approx 1975-1980.
Hope this helps. Michael

dalstott -
Thank you and Sinn very much for answering my query. Chuck Maddox, Jeff Stein, and myself are Excel O Graph owners and have occasional discussions over at "On The Dash". We are accumulating knowledge of this watch and its derivatives bit by bit though not much is known. My view is that Excelsior Park may have made them for all the brands we have identified (Gallet, Excelsior Park, Sinn, Elka).

Now we have another variant of the Excel-O-Graph for the Sinn fans.