This is a 12x6E 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 REQUIRES: ALL props require balancing, this is VERY important, use TOPQ5700. May need prop reamer, use GPMQ5005 (SAE) or GPMQ5007 (Metric) SPECS: Diameter: 12" Pitch: 6 Hub inner diameter: 0.25"