Replacement 1 Micron 100% Synthetic Microglass Fuel Filter (1-12 Thread Pitch) For Duramax Auxiliary Fuel Filter Kit. WIll also fit as a longer option on the Billet Aluminum OEM Filter Adapter when used with corresponding nipple. Filter is approx. 8.5″ long and contains roughly twice the media of the Short 1 Micron Fuel Filter. If you have the Duramax Aulilary Fuel Filter Kit with 2 Micron CAT 1R-0749 filter (Yellow Color), you should purchase this filter instead.