ArmaLite AR-10 B-Series Gen II Rifle Magazine .243/.308 Win 25 Round Black 1 Pack Aluminum. Made of Aluminum with a stainless steel spring. Note; Compatible with Armalite AR-10 B-Series Rifles. Specifications for ArmaLite AR-10 B-Series Gen II .243/.308 Win 25 Round Rifle Magazine: Manufacturer: ArmaLite Color: Black Fabric/Material: Aluminum Magazine Capacity: 25 Round Caliber: .223 Remington Gun Make: AR Platform Package Contents: ArmaLite AR-10 B-Series Gen II .243/.308 Win 25 Round Rifle Magazine ArmaLite 10607003-25RD: AR-10 B-Series Gen II Rifle Magazine .243/.308 Win 25 Round Black 1 Pack Aluminum