Designed specifically for the .40 S&W Px4 Storm, this genuine Beretta replacement magazine gives you the same performance and durability as the gun's original magazine. A great choice as a replacement or convenient spare, this durable magazine features durable stainless steel construction with strict tolerances for long life. Extended design holds 17 rounds of .40 S&W ammunition. Mag also features grip extension on the bottom for better control of gun during use. Manufacturer model #: JM4PX4017. Replacement or spare magazine for .40 caliber Px4 Storm SubCompact Extended design - 17 round magazine capacity Strong stainless steel construction under strict tolerances Grip extension on bottom for greater gun control