Anderson B2M400A000: Accepts Glock Style 9mm Magazines - Comes partially assembled includes: - Magazine Catch and Ejector - Designed for last round hold open - Uses standard AR-15 lower parts - Machined from 7075 T6 Aluminum - Receiver Finish: Type 3 hard Anodized Black - Lowere Receiver Material: Forged 7075 T6 Auminum - Trigger Guard: Open Trigger - Weight: 5.000 - RF-85 Treated: Non-Treated