This is a 13x4 Sport composite propeller from Advanced Precision Composites. FEATURES: Comes in a bag attached to a header card Gray composite one-piece construction INCLUDES: One APC 13x4 sport composite propeller REQUIRES: ALL props require balancing, this is VERY important, use TOPQ5700. May need prop reamer, use GPMQ5005 (SAE) or GPMQ5007 (Metric) SPECS: Diameter: 13" Pitch: 4 Hub inner diameter: 0.25" cdh8/26/03 ir/jxs