This is the GrimRacer 40x52 Three Blade 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 SuperVee 27 Brushless 40x52 Three Blade Metal Boat Prop REQUIRES: Installing on propeller shaft SPECS: Diameter: 40mm Pitch: 52mm Bore: 3/16" COMMENTS: Equivalent to the Octura 440 and the Prather 220 props (not carried) 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.