Billet 4" Inch Turbo Inlet Guard Velocity Stack Adapter Bellmouth PERFECT FITMENT FOR GT3582 Turbochargers This velocity stack features smooth funnel shaped inlet to help air flow. Made of billet aluminum Optimizes volumetric flow rates into your induction system by preventing boundary layer separation at the inlet of your induction system. The large hex shaped filter design creates an induction system that will help keep larger debris out of the turbine and/or engine. For use with 4" Turbo and/or N/A intake inlet applications. Includes locking screw & thread sealer.