The Alpha Precision Brass Catcher Shell Catcher Bag offers a practical solution for collecting spent brass with a removable Picatinny mount for quick attachment and detachment. The mounting plate can remain on the firearm for convenience, while the adjustable adapter allows flexible positioning before or after optics. Ensure sufficient Picatinny rail space for secure attachment. The set includes the brass catcher, adapter plate, and mounting key, providing a high-quality and adaptable accessory for various firearms.