This unique design fits in the magazine well and locks into place to keep the AR safe and secure at home, during travel or on the range. Once the AR MagVault is locked into place a round cannot be inserted or chambered. The AR MagVault features an easy-to-operate key lock system and fits virtually all .223/5.56 AR carbine rifles. It is constructed from extremely durable glass-reinforced nylon for maximum durability.