The 3M™ DF series filter media consists of 2 layers with the first layer being “open” to remove the larger contaminants while the second layer is “tighter” to remove the smaller contaminants. Our graded porosity structure provides greater contaminant holding capacity and longer life than conventional single layer media. Compared to conventional felt filter bags, 3M DF series filter element provide up to 4 times the service life, superior contaminant reduction efficiency, enhanced flow per filter and reduced losses associated with frequent filter change-outs.