Automobile manufacturers continue to strive for improved vehicle performance and increased reliability. Next to the engine, the most important advancements have come for the automatic transmission. Today's automatic transmissions provide the driver with never before achieved levels of vehicle operation, comfort and handling ease. The latest in electronic controls also provide optimized fuel economy and reduced emissions.Hand-in-hand with performance improvements have come improvements in automatic transmission fluid filtration, and specifically, sump or suction-side filtration. Advancements in filtration media technology have improved efficiency and extended filter life. Nonwoven filtration media, sometimes referred to as felt, have been developed which provide distinct advantages over paper media and mesh screens through a mechanism called depth filtration. Various nonwoven media are in use today which provide a range in filtration performance. Recent developments have shown that further efficiency improvements are possible without sacrificing permeability which is critical to cold temperature performance.