This is an APC 45mm Folding Electric Hub for a 40mm Spinner. This two-piece, gray composite propeller hub goes on each side of the APC folding propeller blades to hold them in place.
The 45mm Folding Propeller Hub can be used with a 40mm spinner or similar, but electric powered aircraft only (not for gas engines). This hub has molded nut insets for easy tightening and includes hardware.
Overall Length: 58mm
Length between Blade Mounting Centers: 45mm
Inner Mounting Diameter: 8mm ID with 30 deg. taper for collets