The Sig Sauer P250/P320 Compact Magazine for .40 S&W/ .357 Sig are designed to fit the Sig Sauer P250 or P320 Pistol. It is constructed of steel in a black finish and designed to hold 13 rounds. This magazine is a Factory Original Replacement Part and is manufactured to the same specifications and tolerances using the same materials as the OEM parts. By doing this, Sig Sauer is guaranteeing the optimal fit and reliable operation of the Sig Sauer P250/P320 Compact Magazine for .40 S&W/ .357 Sig.