Highly recommended in dirty environments. Keep your Ram-Air Filter protected from large debris, bugs, mud, etc... Banks hydrophobic pre-filters Highly recommended in dirty environments. Keep your Ram-Air Filter protected from large debris, bugs, mud, etc... Banks hydrophobic pre-filters use uniform micron openings to keep your Ram-Air intake filter element clear from dust and large debris while repelling moisture. Cold and Heat resistant up to 400 degree F. Fits Ram-Air Filter PN 41835/41835-D Banks pre-filter wraps are designed to work with your Ram-Air intake system. Constructed from a polyester mesh (with uniform micron openings) for improved filtering of larger debris and dirt. Also treated to repel water improving performance in humid or wet environments. Resists heat over 400 degrees and will not shatter in freezing temperatures. By blocking larger debris, your Banks Ram-Air filter is able to breathe easier longer, not only improving performance, but also increasing the time between services.