K&N High-Flow Clamp-On Air Filter, Round Tapered 4" Flange × 9" Height — Reusable, Pre-Oiled Performance

The K&N RE-0870 is a washable, reusable clamp-on high-flow air filter (round tapered) designed to increase airflow and last the life of your vehicle.

This universal clamp-on filter combines multi-layer cotton gauze media, a pliable rubber flange, and rugged construction to offer a simple performance upgrade for many engines and aftermarket intakes. Built for clamp-on installations, the RE-0870 has a 4 inch flange diameter, 1.75 inch flange length, and a 9 inch overall height — dimensions suited to a wide range of applications where a cone-style, round-tapered filter is required. It ships pre-oiled and ready to install, and because it’s washable and reusable it reduces replacement waste compared with disposable filters.

How does this filter boost engine airflow and performance?

The RE-0870 uses layered cotton gauze media with a tack-treated finish to allow increased airflow while capturing contaminants. Improved flow can help throttle response and maintain power delivery without modifying the intake system. K&N’s design balances filtration efficiency and airflow for common street and mild performance uses.

• Four layers of premium cotton gauze for staged filtration
• Specially designed tacking agent to trap dirt while preserving flow
• Pre-oiled and optimized media for immediate use
• Engineered to be compatible with many aftermarket intakes and factory housings

What are the exact dimensions and fitment details I should check?

Confirm your intake pipe or clamp location accepts a 4 in flange diameter and that a 9 in height fits the available space. The flange length of 1.75 in provides a secure clamp surface; measure clearance for a tapered, cone-style shape when choosing the RE-0870. Universal clamp-on design offers broad compatibility but always verify physical fit before purchase.

• Flange diameter: 4 in (direct clamp interface)
• Flange length: 1.75 in (clamp engagement area)
• Filter height: 9 in (overall vertical clearance)
• Shape: round tapered (cone-style) for performance intakes

How often will I need to clean it and what's involved?

K&N filters are washable and reusable; under typical highway driving they recommend cleaning about every 75,000 miles (roughly five years by average annual mileage). Cleaning involves a K&N-approved cleaner, rinse, air-dry, and re-oiling to restore filtration characteristics. Routine inspection is advised in dusty or off-road conditions where more frequent service may be necessary.

• Normal service interval: ~75,000 miles (approx. 5 years)
• Use K&N cleaner and oil for best results
• Simple rinse, dry, and re-oil process — no replacement parts needed
• Inspect more often in dusty environments

What materials, warranty, and origin details matter?

The RE-0870 is built with durable molded rubber for a flexible flange that resists vibration and secures the clamp. The media construction and manufacturing methods emphasize long life; K&N backs the filter with a 1-year limited warranty. Filters are proudly made in the USA and are intended to reduce disposable-filter waste by offering a reusable alternative.

• Durable molded rubber flange absorbs vibration and seals securely
• Premium cotton gauze media with multiple layers for filtration
• 1-year limited warranty from K&N
• Made in the USA and designed for long-term reuse

Who this is for: The K&N RE-0870 suits DIY mechanics, aftermarket intake installers, and performance-minded drivers who need a clamp-on cone filter with a 4 in inlet and 9 in height. It’s a practical choice for people seeking a reusable, pre-oiled filter that balances airflow and filtration, reduces waste from disposable filters, and fits many universal intake setups. Verify measurements for proper fit and follow K&N cleaning instructions to maintain performance over time.