Uni Filter NU-3801ST Two Stage Foam Air Filter for Motorcycles and ATVs

The Uni Filter NU-3801ST is a premium two-stage foam air filter engineered for competition motorcycles and ATVs. This best-selling replacement filter is designed as a direct fit for factory air boxes, offering superior performance and protection for off-road applications.

Key Features:

• Unique two-stage foam design with dual layers that can be serviced separately for thorough cleaning
• Drop-in replacement fits factory air box exactly like the original filter
• Thin Ultra Seal foam base is virtually tear-proof and features an integrated "Grease Groove" for superior sealing
• Complete cleaning capability allows for extended service life and consistent performance
• Trusted by factory Yamaha, Kawasaki, and Suzuki off-road racing teams

The NU-3801ST's dual-layer foam construction provides excellent filtration while maintaining optimal airflow. The innovative two-stage design allows each foam layer to be cleaned and oiled independently, ensuring maximum filter efficiency and longevity. The Ultra Seal base prevents tearing during installation and removal while the grease groove ensures a secure, leak-free seal against the air box.