This is a 9x9 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 five adapter rings that adapt to different motor shafts Comes in a bag attached to a header card INCLUDES: One composite propeller Five composite adapter rings One instruction sheet REQUIRES: ALL props require balancing, this is VERY important, use TOPQ5700. May need prop reamer, use GPMQ5005 (SAE) or GPMQ5007 (Metric) SPECS: Diameter: 9" (229mm) Pitch: 9 Hub inner diameter: 0.25" (6mm) mcw 6/8/04 ir/jxs