Heckler & Koch Rifle Magazine MR556 5.56mm 20 Rounds Black 12. Will fit and work in all AR-15/M16 weapons. Perfect for those who need a lower profile magazine or who will be doing prone or bench shooting. Specifications for Heckler & Koch MR556 5.56mm 20 Round Rifle Magazine: Manufacturer: Heckler & Koch Color: Black Fabric/Material: Steel Magazine Capacity: 20 Round Caliber: 5.56x45mm NATO Gun Make: Heckler & Koch Gun Model: Heckler & Koch MR556 Gun Type: Rifle Quantity: 1 Package Contents: Heckler & Koch MR556 5.56mm 20 Round Rifle Magazine What firearm models does the manufacturer say Heckler & Koch MR556 5.56mm 20 Round Rifle Magazine is compatible with? The manufacturer says that Heckler & Koch MR556 5.56mm 20 Round Rifle Magazine is compatible with Heckler & Koch MR556Heckler & Koch 233609S: Rifle Magazine MR556 5.56mm 20 Rounds Black 12