This is a factory 17-round magazine for the Beretta PX4 Storm chambered in .40S&W. This 17-round magazine has an attached magazine sleeve that lengthens the gri of your PX4 Storm. Its stainless steel body provides the quality and longevity you have come to expect from Beretta.
Also compatible with: CX4 with PX4 magazine well, PX4 Compact .40S&W, PX4 Sub-Compact .40S&W* (Will extend below the base of the grip on a Compact and Sub-Compact)
JM4PX417 is an extended magazine.