This is a 5.1x4.5 Thin Composite Electric Propeller from APC|
For use on Electric powered aircraft only (not for glow engines).
Gray composite propeller blades that assemble onto a propeller hub.
Comes with two adapter rings that adapt to different motor shafts.
One composite propeller
Two composite adapter rings
One instruction sheet
Assembly onto motor or gear drive unit in your Electric plane.
Hub inner diameter: 0.25"