This replacement or spare magazine is compatible with your beretta px4 storm.It is also compatible with px4 compact, px4 sub-compact, and well insert/magazine release.Caliber: 9mm LugerCapacity: 20rdFinish: BlackModel: OEMMaterial: SteelType: ExtendedModel Fit: Px4 StormBrand Fit: BerettaCapacity: 20Magazine Restrictions: The following states have magazine restrictions. Your order will not ship to those states if in violation of these laws and will be subject to cancellation and a 15% restocking fee. California - Limited to 10-round capacity. Connecticut - Limited to 10-round capacity. Colorado - Limited to a 15-round capacity. Delaware - Limited to 17-round capacity. Hawaii - Handguns limited to 10-round capacity Illinois (Cook Co, Aurora, Highland Park) - Pistol mags are limited to 10 rounds. Massachusetts - Limited to 10-round capacity. Maryland - Limited to 10-round capacity. New Jersey - Limited to 10-round capacity. New York - Limited to 10-round capacity. Road Island - Limited to 10-round capacity. Vermont - Handguns limited to 15-round capacity, Rifles limited to 10-round capacity. Washington DC - Limited to 10-round capacity. Washington - Limited to 10-round capacity.