This is a 10x3.8SF thin Composite propeller from Advanced Precision Composites. These are for use on electric powered aircraft only (not for glow engines).

• FEATURES:
  Gray composite propeller blades that assemble onto a propeller hub.
  Adaptable to different shaft sizes with the five adapters.

• INCLUDES:
  One composite propeller
  Five composite adapter rings
  One instruction sheet

• REQUIRES:
  Assembly onto motor or gear drive unit in your electric plane.
  Balancing