ProMag Polymer Pistol Magazine Glock 20 10mm 50-Round Black 50RD. The follower is injection molded and the magazine spring formed from heat treated chrome silicon wire. Specifications for ProMag Polymer Glock 20 10mm 50-Round Pistol Magazine: Manufacturer: ProMag Gun Model: Glock 20 Caliber: 10mm Auto Magazine Capacity: 50 Round Package Contents: ProMag Polymer Glock 20 10mm 50-Round Pistol Magazine What firearm models does the manufacturer say ProMag Polymer Glock 20 10mm 50-Round Pistol Magazine is compatible with? The manufacturer says that ProMag Polymer Glock 20 10mm 50-Round Pistol Magazine is compatible with Glock 20ProMag DRM-A69-50RD: Polymer Pistol Magazine Glock 20 10mm 50-Round Black