The TR-6500FC is a filter cover for use with the TR-6510N, TR-6530N and TR-6590N cartridges. 3M recommends the use of the filter cover to help protect cartridges from damage. It is used to hold the TR-6600 Prefilter or TR-662 Spark Arrestor in place. The TR 6500FC is a filter cover for use with the TR 6510N, TR 6530N and TR 6590N cartridges. 3M recommends the use of the filter cover in order to help protect cartridges from physical damage. The filter cover is also used to hold the TR 6600 Prefilter or TR 662 Spark Arrestor in place. The filter cover may be cleaned and reused, and should be replaced when worn or damaged.