The Air filter - Yamaha YZ125/250 1989-1992, WR250 1989-1997, WR500 1991-1993 is part of the latest collection from Twin Air.. Twin Air filters are slightly smaller than stock filters to increase air space around the filter and improve circulation. The resulting increase in air volume around the filter improves circulation within the airbox. More air means more power for your engine. Flow bench tests have proven that Twin Air filters provide increased airflow while reducing the filters tendency to clog.. Features: • Coarse open-pore foam catches airborne dirt, grime and sand. • Fine open-pore inner foam acts as a second filter to trap the smallest particles while ensuring maximum air passage. • Exclusively formulated adhesive withstands repeated cleanings, even with harsh solvents or gasoline. • Thick, flat foam, greaseless sealing ring ensures maximum contact with your airbox, while acting as a breathable gasket for increased air passage. • Fused outer and inner elements prevent dirt and grime from being lodged between layers.Manufacturer part number: 152206.