This is the GrimRacer 42x55 Metal Boat Propeller from AquaCraft. FEATURES: 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 INCLUDES: GrimRacer 42x55 2-Blade Metal Boat Propeller REQUIRES: Installing on propeller shaft SPECS: Diameter: 42mm Pitch: 55mm Bore: 3/16" CAUTION: Wear eye protection when tuning and working on metal boat propellers. Wear a respirator when filing or sanding these propellers. The dust produced is hazardous to your respiratory health.