To qualify as an Out of Aperture (Exposed to flow) prop, the strut is in the form of a molded housing, intregal with the hull, enclosing the full length of the shaft as well as the void between the shaft and the hull.

It will either be:

Folding the blades are hinged and fold together to reduce the drag when not in use.
Feathering the blades rotate on the hub to reduce the drag when not in use
Fixed or Solid the blades are fixed in place