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 its merino wool counterpart. Instead of pulling moisture into the core, it wicks it away. It dries faster and can be washed and ready to wear within a few hours. This new version also features SmartGrip silicones on the leg bands to prevent them from riding up and bunching.


SilverAir Ultralight Boxer Brief w/Fly
Stone Grey
Stone Grey
Stone Grey
Stone Grey
Polar White
Polar White
Polar White
Polar White
Liquid Blue
Liquid Blue
Liquid Blue
Liquid Blue
Carbon Black
Carbon Black
Carbon Black
Carbon Black
Slate Grey
Forest Green

Boxer Brief w/Fly

$ 30.00

  • Carbon Black
  • Forest Green
  • Liquid Blue
  • Slate Grey
  • Stone Grey
  • Polar White
  • 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


(based on body measurement in inches)


If you don't love your first pair, you can return it within 30 days of purchase for a full refund or a different size.

Customer Reviews
4.7 Based on 49 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.

Rick W.
Hong Kong Hong Kong

Not as perfect as the Merino wool ones

I ordered these because you were out of stock (for a long time) with the S size Merino Wool ones that I love. (Seriously.. after 3 years of wearing still my favourite pair. And I ordered more of them earlier) Your contact said I should try these ultra thin ones. Especially with the hot weather here, but I feel like the fit is a tad different. It feels like the waist is a little higher?! And I don’t like the fly, I don’t need it and not love it. So.. the next time, I will go back to the Merino Wool ones.

A Y Athletics Customer
Sagiv M.
Israel Israel

Best underwear I ever wore

Nothing to add. Title says it all

Patrick H.
United States United States

My favorite underwear

I have tried a handful of top merino underwear brands. Y athletics are my absolute favorite. Super comfortable, breathable with a great fit. I will definitely be purchasing more in the future.

A Y Athletics Customer
Michael S.
United States United States

Comfy - Blue could be more vibrant

I wish the blue was more vibrant, but even still, comfortable and true to sizing chart. They do ride up on the legs a little more than the regular weight underwear. So that can be a little frustrating. But if you’re quarantined on the couch, they’re great to lounge around in!