Wheeler Delta Series, Crowfoot Wrench, For Mil-Spec Barrel Nut, Black, Steel Construction 1199464 The Wheeler Crowfoot Wrenches are professional-grade" hardened steel wrenches specifically crafted to stand up to the rigors of AR-15/LR308 assembly" maintenance" and modification; allowing you to tackle any AR building or maintenance task. Each wrench is purposely-built with precision to exact fitment allowing you to install handguards" muzzle devices" and barrels with confidence.