Washable re-usable cotton gauze replacement filter for 1997-2004 C5 & C5 Z06 Vararam intake systems. Green filters outflow the competition and feature dual layer woven cotton. Woven cotton offers 3 advantages: Thinner, stronger & holds filtering oil better. Green also offers a better pleat design. The pleats are parallel to the width creating a stronger filter with more surface area. If you were to stretch out the pleats it would be larger than a standard cotton filter. Green air filters filter up to 5 microns.