Pre-filter Sheets are used to line Maple Syrup Filter Cones. After Syrup has reached a desired boiling point it is poured through the lined cone to remove any unwanted debris. Micron rating is 15-25. These filters can be reused and washed with hot water. The filters should not lose fibers during the process unless the filter has been brushed and fibers are on the outside surface. These filters are made of food grade polyester fibers.