Pre-Filters help to prevent sand, mud, and dirt, from contaminating the air filter in your 2017-2019 Chevy/GMC 6.6L L5P Duramax. Pre-filters feature a breathable construction with a free-flowing material that allow your filter to breathe while blocking out large debris and contaminants. Find the right pre-filter for your intake system by matching up your filter part number, or by using the filter dimensions. Purchase pre-filters from AFE, K&N Engineering, S&B, and many others at XDP! A pre-filter installs tightly over your air filter and serves as the first line of defense to keep larger debris out of your filter media and help extend cleaning intervals.