Alarm version of the the 4F55.  This was a confusing model due not leastly to the fact that so many models were based on this design.  Try to follow this:  You had a choice of maple or walnut Airlarms .   A few were made in onyx.  The onyx ones proved so popular, they discontinued the wooden ones and just sold the onyx ones.  Then the model was discontinued well before the War in 1940.  Then, well after the War in 1947, the 7H57 was introduced as the Sportsman  with a beveled onyx case but essentially the same model.