Filter GUARD Pre-Filters (formerly Filter GUARD) maximize protection and extend the service interval of your air filter. Each Pre-Filter (also referred to as Filter Wrap) is made for the air filter that it is paired with so they can easily slip on and provide 360-degree protection. The polyester mesh prevents large dust particles and debris that would otherwise clog or damage the filter from reaching the filter media all without significantly affecting airflow. The dry weave material prevents the buildup of dirt and can easily be cleaned with soap and water.