ProMag Sig Sauer MPX 9mm 40 Rounds Pistol Magazine Black 40. Magazine body constructed of a proprietary DuPont Zytel based polymer Injection molded magazine follower Magazine spring formed from heat treated chrome silicon wire. Specifications for ProMag Sig Sauer MPX 9mm 40 Rounds Pistol Magazine: Manufacturer: ProMag Color: Black Fabric/Material: Steel Magazine Capacity: 40 Round Caliber: 9mm Luger Gun Make: SIG Sauer Gun Model: SIG Sauer MPX Package Contents: ProMag Sig Sauer MPX 9mm 40 Rounds Pistol Magazine What firearm models does the manufacturer say ProMag Sig Sauer MPX 9mm 40 Rounds Pistol Magazine is compatible with? The manufacturer says that ProMag Sig Sauer MPX 9mm 40 Rounds Pistol Magazine is compatible with SIG Sauer MPXProMag SIGA24: Sig Sauer MPX 9mm 40 Rounds Pistol Magazine Black 40