FeaturesInjection molded polymer body is lightweight but can withstand the rigors of field useEasy to use winding mechanism ensures proper feeding400 round capacityMetal magazine stemEasy to fill designProvides more firepower than standard extended magazinesHuge gas reservoirCompatibility: For WE Open Bolt GBB M4/M16 and other compatible gas riflesMaterial: Polymer, Aluminum AlloyCapacity: 400 roundsGas Type: Green Gas