2000-2002 POLARIS Xpedition 425 UNI AIR FILTER POLARIS ATV, Manufacturer: UNI FILTER, Manufacturer Part Number: NU-8503ST-AD, Stock Photo - Actual parts may vary. The Uni Air Filter is easy to clean with the Uni Air Filter Cleaning Kit and will help cut the grease and oils down so you are able to reuse indefinitely. 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.