Pre-Filters help to prevent sand, mud, and dirt, from contaminating the air filter in your 2007.5-2010 Chevy/GMC 6.6L LMM Duramax. Pre-filters from AFE, K&N Engineering, Banks, and others are all available at XDP. Pre-filters feature a breathable construction with a free-flowing material that lets air through while blocking larger contaminants. Finding the right pre-filter for your intake can be done by matching up filter dimensions or by using the corresponding filter part number. A pre-filter is installed over your air filter and helps to extend cleaning intervals while also blocking out large debris that might otherwise damage your air filter.