Skip to content

Your Bag

Your cart is empty

But you're full of potential..

Create an account to join Club Knix and earn points on this order

Super Leakproof® Cotton Boybrief

$36.00 USD

Buy 3+ Save 15%, Buy 5+ Save 20%

Absorbs about 6 super tampons

Breathable cotton

More absorbency without the bulk

Machine washable

Color: Twilight Navy

Size:

True to Size

Size:

Size and Fit Guide

Build Your 3-Pack

Super Leakproof® Cotton Boybrief

Color: Twilight Navy

Size:

Size:

Super Leakproof® Cotton Boybrief

Color: Twilight Navy

Size:

Size:

Super Leakproof® Cotton Boybrief

Color: Twilight Navy

Size:

Size:

Free Shipping on orders $100+

Shipping

Shipping

Processing Timelines

Please allow 1-2 business days for our warehouse team to pack and ship your order. During peak periods such as sales, holidays and product launches, please allow up to 4 business days for us to process your order. Once an order is placed, we cannot guarantee any address updates, order changes or cancellations. Orders placed on Friday after 1PM will not be shipped until the following Monday.


Split Shipments

Most orders will ship from a single warehouse. However, we occasionally ship from a combination of warehouse locations, so you may receive your order in multiple parts. If items from your order ship in separate packages, we’ll send you tracking information for each package when it becomes available.

Delivery Timelines

For the most up-to-date delivery time estimates, please refer to the shipping timeline at checkout. Delivery timelines do not include processing times. See above for details. All transit times are measured in business days which are Monday-Friday, excluding holidays.

Please note, all shipping timelines are estimates and are not guaranteed.

We are not able to ship to US territories (including Puerto Rico, U.S. Virgin Islands, Guam, Northern Mariana Islands and American Samoa) at this time.

First Pair Risk Free for 30 Days

Leakproof Underwear, Risk Free

Returns & Exchanges

New to leakproof? Your first pair is risk free for 30 days. Wear them, wash them, and see how they work for your body. Not right for you? We'll refund the item price (original shipping excluded). Prefer a different size or style? We also offer free exchanges. Just email info@knix.com and we'll take care of you.

Purchased leakproof before? Within 30 days of delivery you can exchange for another size, style, or store credit. We're unable to provide refunds on underwear. If you ordered multiple pairs, please open, wash, and wear one pair only before initiating an exchange.

Still have questions? View our full policy here.

Rewards Members Earn 36 Points

Comfort-First Fit

A mid-rise boyshort with full bum coverage.

Heavy Absorbency

Absorbs 6 super tampons worth of liquid—perfect for heavy flow days, overnight protection, and light bladder leaks.

Cozy Cotton-Blend

Soft cotton with a hint of spandex feels luxurious against your skin.

Worry-Free Protection

An innovative floating gusset provides leak protection from every angle.

Easy to Wash

Machine washable just like regular underwear.

Zoom

| Twilight Navy
| Twilight Navy
| Twilight Navy
| Twilight Navy
| General

How to Choose?

Essential

  • Days you don’t need leak protection. Everyday freshness and moisture wicking.
  • tsp
    0 tsp

Heavy

  • Extra peace of mind. For the first days of your cycle, light bladder leaks, or a full night's sleep without a leak.
  • tsp
    about 8-14 tsp
  • pad
    about 1.5-3 regular pads
  • tampon
    about 4-7 super tampons
  • cup
    about 1.5-3 menstrual cups

Light

  • Daily freshness. For sweat, discharge, period spotting, or backup protection.
  • tsp
    about 1-3 tsp
  • pad
    about 1-3 pantyliners
  • tampon
    about 1-3 regular tampons
  • cup
    about 0.5 menstrual cups

Moderate

  • For mid-cycle flow, surprise cough or sneeze leaks, or a really sweaty spin class.
  • tsp
    about 4-8 tsp
  • pad
    about 1-1.5 regular pads
  • tampon
    about 2-4 super tampons
  • cup
    about 0.5-3 menstrual cups

Ultra

  • Ultimate peace of mind. For the heaviest period days, light bladder leaks, unexpected postpartum flow, or overnight protection.
  • tsp
    about 15-20 tsp
  • pad
    about 1.5-2.5 super pads
  • tampon
    about 7-11 super tampons
  • cup
    about 2-3 menstrual cups
FRESH FIX TECHNOLOGY®

Cotton meets patented protection.

A sewn-in, floating liner soaks up about 6 super tampons’ worth of liquid—so you stay fresh, comfortable, and in control.

Soft Top Layer

Gently wicks away moisture to keep you fresh and odor-free.

3.5
Rated 3.5 out of 5 stars
Based on 32 reviews
Total 5 star reviews: 12 Total 4 star reviews: 5 Total 3 star reviews: 6 Total 2 star reviews: 5 Total 1 star reviews: 4
53%would recommend this product
FitRated 0.1 on a scale of minus 2 to 2
ComfortRated 3.7 on a scale of 1 to 5
EffectivenessRated 3.2 on a scale of 1 to 5
Keywords
Keywords
Rating
Ratings
Height
Height
Pant Size
Pant Size
Usage
Usage
Pant Size Purchased
Pant Size Purchased
32 reviews
  • Rated 1 out of 5 stars
    1 week ago
    Not what I wanted

    Not what I thought it was going to be. Not what I wanted

    Kimmie K.
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 1 out of 5 stars
    1 week ago
    Underwhelmed

    I was so hoping these would be great, but I feel like I’m wearing a big saggy diaper.

    Susan W.
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 3 out of 5 stars
    2 weeks ago
    Very comfortable for light days

    I like these but the lining bunches and isn’t very useful when this happens. It would be better if the lining was secured to the panty crotch.

    Kristin D.
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 2 out of 5 stars
    3 weeks ago
    Design flaw

    I like the cotton fabric but these feel like wearing a panty liner with no adhesive backing . I’m not sure why you wouldn’t sew down the “pad” to the shorts so the liner is secure. The dream shorts are far superior IMO.

    Anne B.
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 5 out of 5 stars
    4 weeks ago
    Love

    Great. Works for heavy periods

    Melody F.
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 5 out of 5 stars
    1 month ago
    Cotton boy brief

    My first time trying the cotton boy briefs. They are very comfortable.

    Roxanne H.
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 2 out of 5 stars
    1 month ago
    So close!

    I like the fit of these and the fact that they're cotton, but I hate the floating gusset. It causes terrible leaks into the panty, itself, staining whatever pants you're wearing. It's basically the same as using disposable pads without wings, but the panties are much more expensive. Knix: just make the dream short in a cotton version and extend the gusset higher in the front. That's always been the solution to these panties that leak non-stop.

    Sarah
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 1 out of 5 stars
    1 month ago
    Not comfortable or leakfroof

    The floating gusset is not helpful at all. It moves around a lot, especially when working out or doing daily life tasks. Because the gusset moves, it rides up in both directions, and bleeding goes where it's not supposed to. Very disappointed. I was hopeful, but they aren't usable.

    Jeanette
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 1 out of 5 stars
    1 month ago
    Liner is only sewn in at the top and bottom!!!

    It moves around and doesn't stay in place it's like a large pad just floating around, I wish I would have returned them before I even gave them a chance.

    Lauren
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 4 out of 5 stars
    1 month ago
    4 Stars

    True to size. Soft, comfortable.

    Annemarie
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 5 out of 5 stars
    1 month ago
    Great product!

    Comfortable and do not leak. Only drawback is they show through leggings. I really like them :-)

    Alison W.
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 2 out of 5 stars
    1 month ago
    Disappointed

    I bought these after my previous Knix needed to be replaced. This material is a lot cheaper then the previous one and already fraying after one wear. Not worth the money I spent on it.

    Stephanie F.
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief

Your underwear questions, answered.