This is a 4.5x4.1 thin composite propeller from Advanced Precision Composites. For use on Electric powered aircraft only (not for glow engines). FEATURES: Gray composite propeller blades that assemble onto a propeller hub. Comes with two adapter rings that adapt to different motor shafts. Comes in a bag attached to a header card. 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: 4.5" Pitch: 4.1 Hub inner diameter: 0.25" COMMENTS: Use Speed 400 Electric motors. JiM 04.22.05 ir/jxs