-16%
K&N Universal Adapter 6 Inch Filter 3.5in Coupler K&N Engineering KNN21512-1
K&N Universal Adapter 6 Inch Filter 3.5in Coupler K&N Engineering KNN21512-1
K&N Universal Adapter 6 Inch Filter 3.5in Coupler K&N Engineering KNN21512-1
K&N Universal Adapter 6 Inch Filter 3.5in Coupler K&N Engineering KNN21512-1
K&N Universal Adapter 6 Inch Filter 3.5in Coupler K&N Engineering KNN21512-1
K&N Universal Adapter 6 Inch Filter 3.5in Coupler K&N Engineering KNN21512-1
Click to zoom in

K&N Universal Adapter 6 Inch Filter 3.5in Coupler

KNN21512-1
024844263056
Air Intake Components
20+ Units In Stock - Ships Next Business Day
$ 31.00 $ 25.99
$ 25.99

SKU: 21512-1 | UPC: 024844263056

K&N Universal Adapter 6 Inch Filter 3.5in Coupler

The K&N 21512-1 adapter connects 6-inch diameter air filters to 3.5-inch intake couplers expanding options for custom air intake builds across various vehicles. This versatile component supports unrestricted airflow in performance applications. Constructed for long-lasting use in demanding conditions.

Key Features

  • Expanded Compatibility: Fits 6-inch filter flanges to 3.5-inch tubes enabling broader air filter use in custom setups
  • Engineered Airflow: Design maintains smooth air path for efficient engine breathing and power gains
  • Premium Rubber Build: Flexible high-quality material resists cracking heat and wear over time
  • K&N Warranty Coverage: Protected by K&N limited warranty against defects
  • Secure Connection: Tight seal prevents boost leaks in turbo or supercharged systems

Product Notes

  • Suitable for dry or oiled filter elements in high-performance intakes
  • Inspect periodically and replace if damaged for optimal function
  • Standard ground shipping with tracking provided

Installation Notes

  • Professional installation recommended.
  • Slide coupler end over 3.5-inch tube and align flange with filter base
  • Use K&N clamps for secure mounting without drilling

This Part Fits

Year Make Model Submodel
Universal All Custom Air Intakes All

Why Choose K&N?

  • Decades of air intake innovation since 1969
  • Materials tested for extreme racing conditions
  • Precise manufacturing for consistent results

Frequently Asked Questions

  • Q: Does this adapter work with my custom intake?
    A: Yes it connects any 6-inch K&N filter to 3.5-inch tubing ideal for universal performance builds
  • Q: What material is the adapter made from?
    A: Black rubber compound for flexibility durability and resistance to oil fuels and temperatures up to 350F
  • Q: What warranty applies to this part?
    A: Covered under K&N limited warranty for manufacturing defects with easy claims process

Shipping &amp. Handling

  • Method: Standard Ground
  • Availability: In stock - ships same or next business day
  • Packaging: Protective box 7.25 x 6.75 x 1.5 inches
  • Weight: 0.31 lbs

Request For Information

Have questions about ? Fill out the form below and we'll get back to you by the next business day.
Air Intake Components

Air Intake Components

Air intake components control how filtered air enters the engine, directly affecting throttle response, power output, and fuel efficiency. Upgrading the intake path from the filter to the throttle body is one of the most accessible performance modifications available for nearly any vehicle.Popular UpgradesCold air intake kits are the most common upgrade, relocating the filter to a cooler area of the engine bay and replacing the restrictive factory airbox with a mandrel-bent tube for improved flow. Short ram intakes keep the filter closer to the engine for a more compact installation while still outperforming stock setups. Replacement performance air filters let you upgrade within the factory airbox without changing any tubing, which works well for vehicles where airbox location is optimal.What performance gains can I expect from an air intake upgrade?Gains depend on the vehicle and existing intake setup. Most naturally aspirated vehicles see modest horsepower increases in the 5–15 h...

View Air Intake Components Products
Air Intake Systems

Air Intake Systems

Air Intake Systems, Cold Air Intakes & Performance Intake Parts Shop premium air intake systems, cold air intakes, short ram intakes, air boxes, intake components, intake elbows, mass air flow sensors, scoops, snorkels, recharge kits, silicone couplers, and intake hoses at Black Ops Auto Works. This collection is built for enthusiasts looking to improve airflow, throttle response, induction sound, horsepower potential, and under-hood performance across cars, trucks, SUVs, Jeeps, muscle cars, off-road builds, and supercharged HEMI platforms. Whether you are upgrading a daily driver, Dodge Charger, Dodge Challenger, Dodge Durango, Jeep Grand Cherokee, Jeep Trackhawk, Ram TRX, Ram RHO, Toyota Tundra, Chevy Silverado, Chevrolet Camaro, Corvette, BMW, Cadillac CTS-V, Honda, Hyundai, Infiniti, or a custom performance build, our Air Intake Systems collection includes parts designed for fitment, durability, and real-world performance. Air Intake Systems from Top Brands Shop trusted air ...

View Air Intake Systems Products
K&N Engineering

K&N Engineering

Shop K&N Engineering cold air intakes, reusable air filters, oil filters, cabin filters, fuel filters and performance filtration upgrades at Black Ops Auto Works for cars, trucks, SUVs, diesel builds, off-road vehicles, muscle cars, Jeeps, Mopar platforms and custom performance applications. K&N Engineering is one of the most recognized names in automotive filtration and airflow technology. This collection includes K&N cold air intake systems, high-flow replacement air filters, universal clamp-on air filters, drop-in filters, oil filters, cabin air filters, fuel filters, Dryflow filters, filter cleaning kits, intake adapters, air intake accessories and performance filtration parts for street, towing, off-road, diesel and high-performance builds. Shop K&N Engineering Products by Category Find the right K&N performance filtration upgrade using related Black Ops Auto Works categories. Shop cold air intakes, air intake systems, air intake components, automotive air f...

View K&N Engineering Products
Military & First Responder Discounts

Military & First Responder Discount Program

Black Ops Auto Works proudly honors active duty military, veterans, National Guard, reserves, police officers, firefighters, and EMTs with an exclusive 5% discount on all performance parts and carbon fiber upgrades. Verify instantly and start saving today.

Learn More & Apply

Your cart

×