ProMag Roller Follower Lined Rifle Magazine AR-15 5.56mm 30 Round Black 1 Pack DuPont Zytel Polymer 30RD. It is constructed of DuPont Zytel polymer with injection molded mag follower and mag spring formed from chrome silicone wire. Specifications for ProMag Roller Follower Lined AR-15 5.56mm 30 Round Rifle Magazine: Manufacturer: ProMag Color: Black Fabric/Material: Polymer Magazine Capacity: 30 Round Caliber: 5.56x45mm NATO Gun Make: AR Platform Gun Model: AR-15 Last Chance: Yes Package Contents: ProMag Roller Follower Lined AR-15 5.56mm 30 Round Rifle Magazine What firearm models does the manufacturer say ProMag Roller Follower Lined AR-15 5.56mm 30 Round Rifle Magazine is compatible with? The manufacturer says that ProMag Roller Follower Lined AR-15 5.56mm 30 Round Rifle Magazine is compatible with AR-15ProMag RM30SL-30RD: Roller Follower Lined Rifle Magazine AR-15 5.56mm 30 Round Black 1 Pack DuPont Zytel Polymer