2001-2008 HONDA TRX250EX UNI AIR FILTER HONDA ATV, Manufacturer: UNI FILTER, Manufacturer Part Number: NU-4128ST-AD, Stock Photo - Actual parts may vary. Multi-stage competition off-road air filters. Traps dirt and dust in two layers of foam, the large pore pre-filter captures the bigger particles. The small pore inner filter prevents any engine wrecking grit from reaching the cylinder.