APC Folding Propeller Hub 50mm LPFH4
This is the 55mm Folding Propeller Hub for a 45mm Spinner from APC. Electric powered aircraft only (not for gas engines). 
Two-piece, gray composite propeller hub that goes on each side of the folding propeller blades to hold them in place (blades are not included).
Hub has molded nut insets for easy tightening. 
Overall Length: 63mm
Length between blade mounting centers: 50mm
Inner mounting diameter: 8mm

Dimensions 
Hub Thickness: 0.039" / 10mm
Shaft Diameter: 0.031" / 8mm
Product Weight: 0.39oz / 11.05g
Color: GREY