This is Master Airscrew"s Fiberglass-Filled 12x6 3-Blade Nylon Pusher Propeller. FEATURES: Suitable for any application from training and sport flying to serious competition Factory-balanced 3-blade prop has NACA airfoils and holds true pitch Accurately balanced to create a greater thrust at lower RPM Constructed of glass-filled nylon INCLUDES: 12x6 glass-filled nylon 3-bladed pusher propeller SPECS: Diameter: 12" (30cm) Pitch: 6" (15cm) Hole Diameter: 0.24" (6.1mm) COMMENTS: The general rule for converting a 2 blade prop to a 3 blade is to subtract 1" from Diameter OR subtract 1 from the Pitch. PER MASTER AIRSCREW: All 3- and 4-blade props are balanced dynamically at the factory prior to drilling. The mounting holes are then drilled slightly off center, if required, to properly balance the propeller. As such, the mounting hole may be slightly off center. Master Airscrew assures us this is perfectly normal and will not cause problems during use. Master AirscrewPart MASMA1260TP