This is a 8x4E 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

SPECIFICATIONS
Diameter: 8″
Pitch: 4
Hub inner diameter: 0.25″