Injen Technology?s Hydroshield are designed to enhance the efficiency of any air filter, including Injen?s SuperNano-Web and our 8-Layer oiled cotton gauze air filters. Injen?s Hydroshield is constructed from a proprietary base media and then treated with a hydrophobic water-repellent. Our Hydroshield is UV resistant, can stop contaminants down to .005", is puncture resistant, and has elasticity characteristics which helps the Hydroshield to return to the original shape/position after servicing. Injen Hydroshield-BlackPart No. 1039BLK8.50in. x 9.00in. Oval Base/7.0in. Tall/4in.x8in. Oval Top Black Oval water repellant Pre-filter-Fits X-1023 and X-1029 8 1/2in. x 9.00in. Oval base 7.00in. Tall/4in. x 8in. Oval top