This is a 15x4W Thin Composite Propeller from Advanced Precision Composites. Designed for 3D Fun Flying. FEATURES: Gray composite one-piece construction. Comes in a bag attached to a header card. INCLUDES: One APC 15x4W 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: 15" Pitch: 4 Hub inner diameter: 1.4" jxs 8/17/03 ir/jxs