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USA
- USA
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- USA
- CAN
Ships within 48 hours · Estimated delivery Jul 13 - Jul 18
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Description
K&N Performance Air Intake System (57S-4000)The K&N 57S 4000 Performance Airbox replaces the restrictive factory air filter and air box lid. K&N performance air boxes are designed to dramatically reduce air flow restriction as well as smooth and straighten air flow. This allows your engine to inhale a larger amount of air than the factory air filter assembly. More air means more usable power and acceleration throughout the engine's RPM range. The 57S 4000 Performance Airbox comes with an
The K&N 57S-4000 Performance Airbox replaces the restrictive factory air filter and air box lid. K&N performance air boxes are designed to dramatically reduce air flow restriction as well as smooth and straighten air flow. This allows your engine to inhale a larger amount of air than the factory air filter assembly. More air means more usable power and acceleration throughout the engine's RPM range. The 57S-4000 Performance Airbox comes with an oversized conical K&N high-flow air filter and an injection molded air box lid with the K&N logo embossed on top. The air filter can be used for up to 100,000 miles before servicing is needed depending on driving conditions. This performance air box is relatively easy to install into the air box base with commonly available tools. K&N builds these air box systems to last for the life of your vehicle and they are backed by K&N's Million Mile Limited Warranty. Some K&N 57S Series Performance Airboxes are compliant with the latest TUV emissions and sound regulations. Check the K&N catalog or website for vehicle applications and specific TUV status for each vehicle and air intake.- Guaranteed to increase horsepower
- Designed to improve torque and acceleration
- Replaces entire factory air box and air filter system
- Washable and reusable lifetime air filter
- Easy to install, usually in 90 minutes or less
- Lasts up to 100,000 miles before service is required (depending on driving conditions)
- K&N Million Mile Limited Warranty
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.3 ★★★★★
Based on 264 reviews
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Product Reviews
★★★★★ 3
Eaten by my Thighs
Color: 04-multicolour (4-pack), Size: X-Large
I wanted to love them. Sadly they have let me down.
Pros: natural breathable fabric , super soft and comfortable, cotton panty gussets for feminine health and panty liners will stick!! Yay:). And the colors! They are great!
But here’s the Con. And it’s the con of all cons.
THEY RIDE UP!! Eaten by my thighs. I’m 5’6” and in the general area of 175. I fluctuate depending on how many times I visit the bakery! :) I don’t have a thigh gap but it is not a super tight thigh squeeze. I seldom have thigh climb but these do. I tried two different sizes to see if that made a difference. Nope.
I was miserable at a recent theme park in these. I was wearing long heavy dresses and it was quite awkward to yank these legs down non stop.
They feel amazing and they have all the requirements
1. Soft
2. Comfortable and stretches with you
3. Breathable with nice thin fabric. Not bulky
4. Natural fibers
5. Great colors
If you are a person that is not blessed with Thunder Thighs, please order these. They are great! I wear them at home and to locations that I will not be doing a lot of walking at. I have washed them so many times and they look like new still.
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Reviewed in the United States on October 4, 2025
★★★★★ 5
Best Boxer Briefs for Women!
Color: 09-multicolour (4-pack), Size: Large
I rarely give 5⭐️’s but these deserve it! Hands down, the most comfortable material, stitching, waistband, moisture wicking and overall comfort. They sit right beneath my bellybutton, they wash and dry well and they’re sturdy. I have tried 3 styles and these are the best.
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Reviewed in the United States on February 7, 2026
★★★★★ 5
Super soft and comfortable!
I haven't bought new underwear in forever. I used to wear thongs, but now find them incredibly uncomfortable. The last few times I've tried to buy new underwear, the sizing was either way off (I'm a medium, but gave up after having to return them for a large and then extra large) or the quality was horrible (two brands stretch waaaay out and they can fall down while wearing them (I have larger ass-ets, so they shouldn't start to slide down during use). I tried these after buying some bamboo pyjamas and I love them! They are incredibly soft, comfortable, and stretchy. I can use them all day, and they work well, whether I'm lounging on the couch or wearing them under my spandex shorts at the gym, they don't ride up or slide down. They are both comfortable and look sexy, while providing support in all the right places. I haven't had them too long, so I can't speak on the durability, but they appear to be of good quality and I plan to order more, this time without the band.
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Reviewed in the United States on November 13, 2025
★★★★★ 5
Well made, light fabric. Waist doesn't roll.
These bamboo underwear really do keep you cool.
They fit true to size, and wear easily. the wide elastic waist band doesn't roll on me.
They are comfortable to wear, washed and dried easily.
The material has some stretch to it, but not a lot.
Well made, no stray strings. Perfect fit for me.
Just what I was looking for.
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Reviewed in the United States on May 17, 2026
★★★★★ 5
Good quality, smooth feel
I got these briefs so recently that have washed just one pair so far. First off, these are very comfortable, the material is soft & bordering silky, good quality sewing. Wash well and minimal if any shrinkage. They do come a bit wrinkled from the dryer but hey, these are underwear and will go on smoothly. If it were a t-shirt, I would look sloppy. I feel the sizing is accurate. No rolling and these don't announce themselves under clothing. Planning on getting more of these boxers and replacing my old panties.
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Reviewed in the United States on January 31, 2026