This is a 6x5.5E Thin Composite Propeller from Advanced Precision Composites. For use on Electric powered aircraft only (not for glow engines). FEATURES: Gray composite construction INCLUDES: One 6x5.5E Thin Electric Propeller REQUIRES: ALL props require balancing, this is VERY important, use TOPQ5700. May need prop reamer, use GPMQ5005 (SAE) or GPMQ5007 (Metric) SPECS: Diameter: 6" Pitch: 5.5 Hub inner diameter: 0.25" jxs 10/25/05 ir/jxs