The NBS Mil-Spec Buffer Tube is a quality Receiver Extension (AKA Buffer Tube) machined from high strength American 7075-T6 Aluminum. This is a 6 position design and is a finished with Type 3 class 2 Hard Anodizing. *These are sourced from various manufacturers, and tubes received might vary slightly from batch to batch in regards to finish and design. However, buy with confidence as these are backed by our NBS satisfaction guarantee. American Made 7075-T6 Aluminum Platform: AR-15 Positions: 6 Weight: 3.872 Oz