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Home / Boyshort Underwear / Leakproof Cotton Boybrief
Best Seller

Leakproof Cotton Boybrief

$35.00 USD

Mix & Match: 3+ for $25 each
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Absorbs about 3 super tampons

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Cotton comfort

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More absorbency without bulk

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Machine washable

| Mushroom
| Mushroom
| Mushroom
| Mushroom
| Mushroom
| General

Absorbency: Moderate
Drop
Drop
Drop
Drop
Drop

Color: Mushroom Limited Edition

Size:

True to Size

•

Size:

Size and Fit Guide

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HOLIDAY SHIPPING

Give the gift of Knix! To receive your order by Dec 24th, please order by the following dates.

All States - Urban Centers (except Hawaii, Alaska)
Standard: Sunday, December 14
Express: Tuesday, December 17

Alaska, Hawaii & Rural
Standard: Wednesday, December 10
Express: Wednesday, December 10
Express shipping is unavailable for international orders:

Africa, Central/South America, and Caribbean
Standard: Wednesday, December 10

Asia, Australia, and New Zealand 
Standard: Thursday, December 11

Europe and the Middle East 
Standard: Thursday, December 11

United Kingdom, France, Germany, Netherlands, Switzerland, and Japan 
Standard: Monday, December 15

Please note: Weather conditions and carrier issues may cause delays. Delivery dates are not guaranteed.

Processing Time
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.

Delivery Time
For the most up-to-date delivery time estimates, please refer to the shipping timeline at checkout. Delivery timelines vary depending on location and do not include processing times.

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Orders over $100* USD = Free standard Shipping (4-8 business days)**
Expedited = $4.99 USD (3-6 business days)**

Orders under $100* USD = $7.99 USD Standard Shipping (4-8 days)**
Expedited = $9.99 USD (3-6 business days)**

*After discounts, before shipping and taxes. Processing times not included in estimates.
**Military Addresses Excluded. Standard Military Address Shipping = $10.00 USD (est. varies per location)
Easy Exchanges within 30 Days

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Returns

Free Returns

Knix covers the return shipping fees for exchanges and refunds initiated through our Return & Exchange Portal. Exchange orders initiated through our Return & Exchange portal are also eligible for free shipping within the USA and Canada. Please note, the shipping fees on your original order are non-refundable.

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Return policy varies by product, please check if your item is refund or exchange eligible by viewing our full policy here.

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Items discounted below 30% are eligible for size exchange or store credit. Items discounted 30% and above are final sale – no refunds, store credits, or exchanges can be accommodated.
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Comfort-First Fit

A mid-rise boyshort with full coverage in the bum area.

Worry-Free Protection

An innovative floating gusset provides leak protection from every angle.

Moderate Absorbency

Absorbs about 3 super tampons worth of liquid—great for moderate flow days, light bladder leaks, and sweat.

Cozy Cotton-Blend

Soft cotton spandex feels luxurious against your skin.

OEKO-TEX® Certified

Certified according to OEKO-TEX® STANDARD 100, Product Class I : HK020 246396 TESTEX

Easy to Wash

Machine washable just like regular underwear.

Zoom

| Mushroom
| Mushroom
| Mushroom
| Mushroom
| Mushroom
| General

How to Choose?

Essential

Drop
Drop
Drop
Drop
Drop
  • • Everyday Wear
  • • No leakproof protection
  • tsp
    0 tsp

Heavy

Drop
Drop
Drop
Drop
Drop
  • • heavy period days
  • • overnight protection
  • • light bladder leaks
  • 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

Drop
Drop
Drop
Drop
Drop
  • • light period days
  • • sweat
  • • discharge
  • tsp
    about 1-3 tsp
  • pad
    about 1-3 pantyliners
  • tampon
    about 1-3 regular tampons
  • cup
    about 0.5 menstrual cups

Moderate

Drop
Drop
Drop
Drop
Drop
  • • moderate period days
  • • light bladder leaks
  • • sweat
  • 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

Drop
Drop
Drop
Drop
Drop
  • • extra heavy period days
  • • overnight protection
  • • light bladder leaks
  • 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®

Built-in protection that feels like nothing at all.

Absorbs about 2-3 super tampons worth of liquid.

Soft Top Layer

Soft Top Layer

Gently wicks away moisture while keeping you feeling fresh and odor-free.

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4.3
Rated 4.3 out of 5 stars
Based on 213 reviews
Total 5 star reviews: 141 Total 4 star reviews: 28 Total 3 star reviews: 21 Total 2 star reviews: 8 Total 1 star reviews: 15
80%would recommend this product
ComfortRated 4.4 on a scale of 1 to 5
EffectivenessRated 4.3 on a scale of 1 to 5
FitRated 0.1 on a scale of minus 2 to 2
Ease of UseRated 4.5 on a scale of 1 to 5
Write a Review (Opens in a new window)
213 reviews
  • Rated 3 out of 5 stars
    22 seconds ago
    Boybriefs

    I think the insert should be sewn in better I could feel the insert shifting

    Letha D.
    Verified Buyer
    Was this helpful?
  • Rated 4 out of 5 stars
    29 minutes ago
    Leakproof Cotton Boybrief

    Love the feel and comfort of cotton!

    Sandra C.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    Yesterday
    Oh so comfortable!

    I never need to worry about protection.

    Christa H.
    Verified Buyer
    Was this helpful?
  • Rated 3 out of 5 stars
    Yesterday
    Weirdly comfy

    These are the strangest period undies I've ever tried. I don't straight-up dislike them, but there were some weird choices made making these.

    The main fabric is really thin, which is not usually what I want in cotton, and definitely not what I'd choose for period undies. I'd want it to be a little thicker in case there was some spillage outside the leakproof area.

    I have no idea why the seams would continue all the way up the middle of your butt cheeks if the leakproof fabric doesn't. I did buy them for sleeping in, but the seams make it so I wouldn't want to leave the house in them. Though I don't feel the seams as much as I expected. They are also probably the most unflattering undies I own and somehow look like granny panties and grandpa panties at the same time. Way too high rise for me.

    They are quite comfortable though. And while I'm using them as menstrual cup backup overnight, I do appreciate that the leakproof area is only connected at each end, making it so if you wanted to add a pad for extra coverage, you'd have something to wrap the wings around.

    Jessica G.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    Yesterday
    Awesome fit and comfort

    Fits nice and very comfortable

    Bridget P.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    3 days ago
    Comfort beyond belief

    These are the best fitting and most comfortable underwear I have ever worn! I'm a woman at the age of minor urinary accidents when exercising, sneezing or laughing uncontrollably, which is why Knix are the only brand of underwear I own

    Erika C.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    3 days ago
    Love the fit

    These fit great.

    The crotch would benefit from a top layer of cotton.

    Overall I would recommend these.

    Bernadette R.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    4 days ago
    Leakproof cotton boy brief

    Love them

    Deborah S.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    6 days ago
    period protection but still so comfy!

    I use these undies for my period and also every day wear but this was my first time getting the cotton ones and I think I've been converted to these undies for now on!

    Paige S.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    1 week ago
    Favourite cotton cut so far!

    I have many different models of Knix moderate to heavy flow undies. These are my favorite model in their cotton options.

    Roelle M.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    1 week ago
    5 Stars

    Great products great shape

    Gina
    Was this helpful?
  • Rated 5 out of 5 stars
    1 week ago
    Comfy and fits well

    These fit me very nice and don’t ride up on me. I wear more for sweat and urine absorption due to urinary incontinence and they works great. I am dry and no more pads! Easy to care for as well.

    Jacquelyn W.
    Verified Buyer
    Was this helpful?