A lighter and stronger take on underwear, we created the fabric with plenty of nylon for strength, modal for softness, spandex for stretch, and SilverAir yarns for odor resistance. The knit structure of the fabric is open and breathable, and works very differently than our Merino Wool Underwear. Instead of pulling moisture into the core, it wicks it away. While the anti odor performance will not be as effective as our merino products, it dries faster and can be washed and ready to wear within a few hours. This product does not feature the SmartGrip System found in our Merino Wool underwear; otherwise, the construction and components are identical.


SilverAir Ultralight Boxer Brief
Carbon Black
Carbon Black
Carbon Black
Carbon Black
Stone Grey
Stone Grey
Stone Grey
Stone Grey
Polar White
Polar White
Polar White
Polar White

Boxer Brief Flyless


$ 28.00

  • Polar White
  • Stone Grey
  • Carbon Black
  • S
  • M
  • L
  • XL
  • XXL
    • Lightweight open-knit fabric dries quickly
    • SilverAir Technology reduces odor
    • Double soft waistband doesn't roll over or leave marks
    • 50% Nylon, 35% Modal, 10% Spandex, 5% Metallic
    • Manufactured in China


We want you to love your gear and offer a try-on guarantee for your first pair of underwear. If you don't love it, let us know within 30 days of purchase and we'll send you a different size or take it back and issue a full refund.

Customer Reviews

4.8 Based on 30 reviews
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Joseph H.
United States

Great workout/everyday underwear

I've owned a number of premium underwear brands, including Y's own SilverAir Merino variety. The fit of these is pretty much the same, which is to say it's very good. Enough support for workouts and HIIT, but not too much so that it's still very comfortable to wear as a daily driver. In fact, they are one of the most comfy boxer briefs I've ever worn. Compared to the merino underwear, these are a lot lighter and airier. The merinos are great to wear as travel underwear, as well as for gym days. These new ones would be equally good for gym days, but I'd feel a lot better about running in them since they're so much lighter. I can't attest to the durability of these yet since they're brand new, but because they are so thin and light, I hope they hold up as well as some of my other premium activewear. We'll see! Otherwise, highly recommended.

George F.
United States

Fabulous Underwear

My third order of my favourite socks and underwear. Never worn any more comfortable.

James W.
United States


Still no loop to hang underwear from; only got half credit for a pair that ripped into a giant hole after two years (I'm an original KS backer).

Joshua O.
United States


I accidentally bought the wrong underwear that I wanted, but your products are so good that I’m extremely happy with what I got anyways. I backed the original stuff on Kickstarter years ago and I still have my socks and shirts. They’re amazing. I also want to say thank you for the free nylon bag that came with my order. It was a wonderful surprise. If anyone actually reads this, I hope your company continues to deliver a great quality product! I will be buying from you again.

Fernando L.
United States

Great Concept Idea still needs some tweaks.

I love how light they are, how great they feel and the ventilation they provide. However, unlike the SilverAir Merino Wool Boxer Brief w/Fly, these do not have the proprietary grip that would keep them from riding up. Which was an issue here and there. Besides that I love the concept. If they add the grip I will definitely buy more in the future.