They form a seal to prevent outside air from leaking into the injectors or fuel vapours from escaping. Part Number: 16636-0B010 Fitment : Fit for Nissan: 1999-2004 Frontier 1999-2002 Quest 2000-2004 Xterra Includes: 6 X Lower Fuel Injector Seal O-Ring Support: 12 Months of Product Service Hassle-Free Return and Refund Policy. [High Quality]Made of High Quality Material, Durable, Stable Performance, Strong Reliability, Long Service Life 10pcs Engine Fuel Injector O-Ring Seal For Mercedes R170 W202 0199971348 ] Please confirm the model, displacement and year of your car before purchasing. Ship Content:12 Pcs O-rings6 Pcs Filter Baskets Nice: [SIMPLY TO USE] It could correctly replace the originally parts, no tools required to install. About: [REPLACE PART NO. Fuel Injector Seal Kit Motoforti Fuel Injector Seal O Ring - Car O-Ring Rebuild Repair Kit - For Mercedes-Benz 3.5L 2005-2013 NBR Rubber Black - 6 Sets Long-lasting, Seal Kits - Canada Fuel Injector Seal O-ring Injector seals and O-rings aid to create vacuum pressure so that injectors may work correctly in the vehicle's engine. A ABSOPRO Fuel Injector Seal O Ring - Car O-Ring Rebuild Repair Kit - for Mercedes-Benz 3.5L 2005-2013 NBR Rubber Black - 6 Sets Item Replacement in Seal... Function:Injector seals and O-rings help provide vacuum pressure for injectors to function properly in the engine of the vehicle. They provide a seal to ensure no outside air leaks into the injectors or fuel vapours leak out.