What separates the Attack Blue filter from others is its unique low restrictive open mouth and tapered back design, which allows more free flowing air to rush through the filter. The end result is more power, torque and quicker throttles response! No surging. No tune needed. Drop it in and go. When Magnuson Supercharger was looking for a filter for more power, they chose Attack Blue for their system. When stock filters clog, it results in a loss of power. Attack Blue's woven cotton media and deep pleats create a larger filtration surface which allows a greater volume of air to move freely to your engine while maintaining superior filtration! Traps particles as small as 5 microns! The Attack Blue is washable and reusable. Reinforced design prevents warping and leaking. IMPORTANT: All 2009-2013 ZR1's and Late 2012 and all 2013 C6, Z06, and Grand Sport require the GM filter retainer (CC #156192). The reason for this is the retainer is glued to the stock filter for those years.