I collect APFK Model #1's..... but I have a sleeper in the bunch.

This is a model #5 with a 7" blade. Note the lack of the finger dip on the spine at the hilt. The top edge is not sharpened...... but, it has a double hilt!

The handle is a great piece of stag with a brass pin.

The sheath is a wide flap Heiser.... Knife and sheath are early 50's.