Lug-Lok Upper Vise BlockUses strength of barrel lugs to secure upper Secure the upper at multiple optimum working angles Critical functionality: torquing barrel nuts, changing flash suppressors, installing handguards, adding accessories to a picatinny rail, building or customizing Traditional clamp style upper blocks fit poorly and can exert enough inward pressure to damage the receiver when applying torque to a barrel nut or flash suppressor. That*s bad design. So, we