K&N High-Flow Clamp-On Air Filter RU-4740 — 4.5-inch Flange, 6-inch Tapered Washable Reusable

K&N High-Flow Original Universal Clamp-On Air Filter RU-4740 is a washable, reusable tapered clamp-on filter that increases airflow while providing durable, long-lasting engine protection.

This K&N clamp-on air filter is built to fit a wide range of intake setups and offers performance-minded drivers a reusable alternative to disposable paper elements. The RU-4740 features a 4.5-inch molded rubber flange and a 6-inch overall height in a round, tapered (cone-style) shape that works for many custom and replacement applications. Pre-oiled and ready to install, it’s engineered to let more air reach the engine without sacrificing filtration quality.

How does this filter affect engine breathing and performance?

The multi-layer cotton gauze media is designed to move more air into the intake than a typical paper filter, which can translate to improved throttle response and potential horsepower gains on many engines. K&N achieves increased flow by using a dense but porous cotton mesh treated with a tackifier that helps trap contaminants without overly restricting airflow.

• Four-layer cotton gauze construction for enhanced airflow and filtration.
• Pre-oiled media ready to catch particles after installation.
• Tapered cone shape encourages smooth intake flow into the throttle body.
• Engineered to maintain airflow as the element collects debris.

Will the RU-4740 fit my setup and how easy is installation?

This clamp-on filter is made with a pliable molded rubber flange that compresses to fit onto 4.5-inch diameter inlets and absorbs vibration for a secure fit. Because it’s a universal-style clamp-on unit, it’s common in custom air-intake builds, replacement airboxes, and aftermarket intake tubes where a tapered filter is required.

• 4.5 in flange diameter, 0.625 in flange length for secure clamp mounting.
• 6 in overall height and round tapered profile fits many cone-style applications.
• Pliable rubber flange simplifies mounting to varied tubing finishes and angles.
• Pre-oiled: no initial oiling step required for most installations.

How does maintenance work and what is the service interval?

K&N filters are washable and reusable, which reduces recurring costs and landfill waste compared with disposable filters. For normal highway driving, K&N recommends cleaning approximately every 75,000 miles, but frequency should increase with dusty or off-road use.

• Wash and re-oil procedure uses K&N cleaning kit or compatible products.
• Typical cleaning interval: up to 75,000 miles under normal highway conditions.
• Inspect more often in dusty/off-road environments to protect the engine.
• Durable construction intended to last for the life of your vehicle.

Who is this product for?

The K&N RU-4740 is aimed at vehicle owners, hobbyists, and performance enthusiasts who want a universal clamp-on cone filter that improves airflow, cuts long-term filter costs, and reduces landfill waste. It’s a good choice for custom intakes, replacement applications requiring a 4.5-inch flange, and anyone who prefers a washable, durable filter built in the USA with a manufacturer-backed warranty.