This is the GrimRacer 42x55 Metal Boat Propeller from AquaCraft.
Constructed of high quality Copper-Beryllium-Titanium material that is rigid but not brittle and can be sanded and shaped with less effort than Stainless Steel props Copper-Beryllium-Titanium material stays sharper longer and is less prone to dulling and chipping. True center bore hub with raised letters and numbering for easy identification. Tumbled to remove any excess cast flashing.
Diameter : 42mm
Pitch : 55mm
Bore : 3/16 in.