This magazine is compatible with your fn 509.*note- will not work with fns tm or fnx tm series pistols.
Caliber: 9mm Luger
Capacity: 17rd
Finish: Black/FDE
Model: 509
Material: Stainless Steel
Type: Detachable
Model Fit: 509
Brand Fit: FN
Capacity: 17
Caliber: 9mm Luger
Capacity: 17rd
Finish: Black/FDE
Model: 509
Material: Stainless Steel
Type: Detachable
Model Fit: 509
Brand Fit: FN
Capacity: 17