The 3M™ Versaflo™ Filter Cover, TR-6700FC is a filter cover for use with the 3M™ Versaflo™ Filter, TR-6710N. 3M recommends the use of the filter cover in order to help physically protect the 3M™ Versaflo™ Filter, TR-6710N from damage.It is also used to hold the 3M Versaflo Prefilter, TR-6600 or 3M Versaflo Spark Arrestor, TR-662 in place. The 3M Versaflo Filter Cover, TR-6700FC should be replaced when worn or damaged.