This magazine is compatible with your FN FNX. It features a polished stainless steel body with a flat dark earth polymer base pad.
Specifications:

Caliber	45 ACP
Capacity	15
Finish	Stainless Body/FDE Base Pad
Model	FNX-45
Material	Stainless Steel
Type	Detachable
Model Fit	FNX-45
Brand Fit	FN
Max Capacity	15