ProMag Polymer Pistol Magazine MP5/PTR9 9mm 50-Round Black 50RD. The follower is injection molded and the magazine spring formed from heat treated chrome silicon wire. Specifications for ProMag Polymer MP5/PTR9 9mm 50-Round Pistol Magazine: Manufacturer: ProMag Magazine Capacity: 50 Round Caliber: 9mm Luger Gun Model: Heckler & Koch MP5 Magazine Type: Drum Package Contents: ProMag Polymer MP5/PTR9 9mm 50-Round Pistol Magazine What firearm models does the manufacturer say ProMag Polymer MP5/PTR9 9mm 50-Round Pistol Magazine is compatible with? The manufacturer suggests that ProMag Polymer MP5/PTR9 9mm 50-Round Pistol Magazine is compatible with Heckler & Koch MP5ProMag DRM-A106-50RD: Polymer Pistol Magazine MP5/PTR9 9mm 50-Round Black