Real Avid has a deep understanding of what it takes to build or trick-out a quality AR-15. That's why they weren't satisfied with the cheap, poorly designed tools on the market and created the Armorer's Master Wrench. Beautifully ergonomic to give you the serious torque needed to remove stubborn, crusted-on barrel or castle nuts without marring your firearm or stripping the nuts. Same goes for your flash suppressor. Repeated high-temp heating/cooling cycles cause the threads to become nearly welded. It takes a lot of hand-numbing torque to break them free.