This is the APC Electric 5.5X4.5 RC Plane Propeller

Speed 400 Electric
Use LPAR18SF or LPARM12SF adapter rings
Includes one set of rings from LPAR18SF and LPARM12SF

Pitch (inches): 4.5
Propeller Diameter (in.): 5.5
Hub Diameter: 0.50 in.
Hub Thickness: 0.30 in.
Shaft Diameter: 1/4 in.
Product Weight: 0.14 oz.
Color: GREY