This replacement or spare magazine is compatible with your FN FNX. It is constructed of heat treated steel with injection molded mag follower and mag spring formed from chrome silicone wire. Made in the USA.
Specifications:

Caliber	45 ACP
Capacity	15
Finish	Blued
Model	FNX
Material	Steel
Type	Detachable
Model Fit	FNX-45
Brand Fit	FN
Max Capacity	13