


K&N Unique Air Filter - Replacement Element for RK-3931
Marsoni
M251S
Get it in 3 business days with 1 day shipping.
Friday, May 29
K&N Unique Air Filter - Replacement Element for RK-3931The K&N replacement air filter for RK Series air cleaner assemblies is designed to increase horsepower and acceleration while providing excellent filtration. The air filter is washable and reusable and designed to be used as a replacement air filter for specific K&N RK Series air cleaner assemblies for Harley Davidson motorcycles. The air filter is covered by the famous K&N Million Mile Limited Warranty.
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Your K&N Unique Air Filter - Replacement Element for RK-3931 orders ship within 1-2 business days.
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- Standard: 3-7 business days
- Fast: 2-3 business days
- Express: 1-2 business days
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Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
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4.9 ★★★★★
Based on 1529 reviews
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Product Reviews
★★★★★ 5
fits my Sienna 2006 with a little adjustment - sturdy, clean and happy that I brought it
Size: 8.3" x 8.4" x 0.6"
I brought this for my Camry 2006 and I have a Sienna 2004 as well that use the same regular cabin filter with the exact model. But when I put this K&N filter on my Sienna it doesn't fit well. The K&N filter sits in the plastic cabin filter frame exactly but there are four little plastic square on the side of the plastic frame sticking out that were in the way. I trim off the K&N border a bit and also the frame too in order to fit in. Beside a little adjustment, it works perfectly for my Sienna 2004. The smell is gone. I also use an oil pen to note on the K&N filter that "Do not replace" in case the dealer replace it during a maintain. I would buy more but this is life time I will buy another one for my camry. I am more than glad introducing this to my friends
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Reviewed in the United States on April 2, 2015
★★★★★ 5
Te ahorra dinero y tiempo
Size: 8.3" x 8.4" x 0.6"
Un filtro de muy buena calidad, lo recomiendo ya que se puede lavar y uno se ahorra mucho dinero
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Reviewed in the United States on December 24, 2025
★★★★★ 5
Make sure it fits your vehicle cabin filter.
Size: 8.3" x 8.4" x 0.6"
I like that it last long and I don't need to buy replacement every time a funky smell starts appearing after turning on the car or truck AC or heater. Saves money by easy to maintain without replacements.
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Reviewed in the United States on October 12, 2023
★★★★★ 4
buen material
Size: 8.3" x 8.4" x 0.6"
Es una buena compra excelente producto calza perfectamente en mi Fj cruiser 2011, en cuanto a su durabilidad lo diré cuando pueda hacerlo por lo pronto está instalado cuando haga los primeros lavados volveré a comentar si se mantienen en buen estado como promete. Lo que difiere con el original es que un lado va para abajo el que tienen una felpa tipo algodón y el otro para arriba en cambio en este filtro de cabina K&N no se sabe cual lado ba abajo o cual arriba, por eso menos una estrella
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Reviewed in the United States on February 10, 2026
★★★★★ 5
It works as advertised
Size: 8.3" x 8.4" x 0.6"
The one thing I haven't found out is if the product will remove exhaust smells - I don't believe it will, but the nice thing is that air flows a little bit better then the Toyota FJ carbon filter that was in there. I don't believe the previous owner even knew it had a cabin filter. Glad to have this in there.
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Reviewed in the United States on August 24, 2023