This is the 4.7x4.2 Speed 400 Electric Propeller from Advanced Precision Composites. FEATURES: Gray composite propeller that assembles onto a propeller hub Comes with two adapter rings that adapt to different motor shafts INCLUDES: One composite propeller Two composite adapter rings One instruction sheet REQUIRES: ALL props require balancing (use TOPQ5700) May need prop reamer, use GPMQ5005 (SAE) or GPMQ5007 (Metric) SPECS: Diameter: 4.7" Pitch: 4.2 Hub inner diameter: 0.25" CCOMMENTS: Use with Speed 400 Electric motors. cnh 3/26/09 ir/jxs