The Real Avid® Lug-Lok® Upper Vise Block offers reliable stability without exerting inward pressure on your receiver, effectively protecting your firearm from damage when torquing barrel nuts, changing flash suppressors, installing handguards, and adding accessories to Picatinny rails. The Lug-Lok is precision machined for a precise fit in all Mil-Spec uppers, mating perfectly with barrel lugs for a reliable hold. 2 vise pins allow you to hold the upper at multiple working angles and prevent unwanted rotation during high torque application, while the integrated lock knob keeps the tool safely seated into the barrel lugs to prevent unintentional movement or damage.