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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

Front view of model wearing the Super Leakproof® Cotton Boybrief, highlighting the coverage and fit
Super Leakproof® Cotton Boybrief shown front-facing against a light gray background
Back view of model wearing the Super Leakproof® Cotton Boybrief, highlighting the coverage and fit
Full-body view of model wearing the Super Leakproof® Cotton Boybrief, highlighting the coverage and fit

Color: Dusty Pink Limited Edition

Size:

True to Size

•

Size:

Size and Fit Guide

Build Your 3-Pack

Front view of model wearing the Super Leakproof® Cotton Boybrief, highlighting the coverage and fit

Super Leakproof® Cotton Boybrief

Color: Dusty Pink Limited Edition

Size:

Size:

Front view of model wearing the Super Leakproof® Cotton Boybrief, highlighting the coverage and fit

Super Leakproof® Cotton Boybrief

Color: Dusty Pink Limited Edition

Size:

Size:

Front view of model wearing the Super Leakproof® Cotton Boybrief, highlighting the coverage and fit

Super Leakproof® Cotton Boybrief

Color: Dusty Pink Limited Edition

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

Holiday Return Policy
Eligible items purchased online or in stores between November 2, 2026 and December 31, 2026 may be returned through January 29, 2027. All other purchases fall under our 30 day Returns Policy.

Standard Return Policy
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 your regular underwear.

Zoom

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.

3.3
Rated 3.3 out of 5 stars
Based on 50 reviews
50%would recommend this product
FitRated 0.1 on a scale of minus 2 to 2
ComfortRated 3.5 on a scale of 1 to 5
EffectivenessRated 3.1 on a scale of 1 to 5
Keywords
Keywords
Rating
Ratings
Height
Height
How do you use your Leakproof?
How do you use your Leakproof?
Usual Pant Size
Usual Pant Size
50 reviews
  • Rated 1 out of 5 stars
    Yesterday
    Irritating Seams

    I don't often write reviews but feel compelled to today after wearing these boybriefs. I have been up and down but still, sitting a fair amount today at my desk and the seams are actually hurting my butt! Super disappointing as the underwear are not cheap. I wouldn't recommend them.

    A
    Amanda
    Verified Reviewer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 4 out of 5 stars
    1 week ago
    Good but

    Like the briefs BUT do NOT like the many liner is LOOSE. Sew it in please. It feels weird floating around

    LJ
    Lisa J. S.
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 4 out of 5 stars
    2 weeks ago
    Cotton Boybrief

    Soooooo soft and comfortable.

    The only thing that prevented me from giving 5 stars was the fact these underwear have a “floating” absorbent pad which means it is only attached to the underwear at the top and bottom; not the sides.

    CE
    Cynthia E. C.
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 2 out of 5 stars
    3 weeks ago
    Not leakproof

    I have several pairs of Knix I love that are completely leakproof. However, the cotton briefs are not one of those. Because the actual pad portion is not fully sewn into the underwear, it shifts around as I do, causing blood to leak around it or seep around to the backside. I am disappointed because I love the fit and cotton, but they are not practical.

    K
    Kendra
    Verified Reviewer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 2 out of 5 stars
    1 month ago
    Uncomfortable

    The stitching up the back of the underwear I runs and is not comfortable at all

    RR
    Richelle R.
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 5 out of 5 stars
    1 month ago
    5 Stars

    Everything came exactly as described

    S
    Sarah
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 4 out of 5 stars
    2 months ago
    A little saggy around my butt

    The pants are very comfortable, but a little baggy around my butt. I understand that I have a small butt, but I never had that issue with Jockey underwear. Other than that, very nice.

    MR
    Maribeth R.
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 5 out of 5 stars
    2 months ago
    5 Stars

    Comfortable, breathable, good leak support.

    S
    Shana
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 1 out of 5 stars
    2 months ago
    Disappointed

    Pieces of the pad came out in the very first wash and got all over my washer. Bought addl pairs and didn’t open them in case the first was bad and found out you can only return with store credit. And customer service is dumb ass AI bots that don’t help at all. Don’t want to purchase from them again.

    KG
    Kate G.
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 1 out of 5 stars
    2 months ago
    They never arrived

    I placed my order received confirmation , then an email saying they were on the way. Tracked to MA post office August 2 and then received email the order is delayed. No follow up, when I responded back on the tracking email I received a separate email requesting I verify my address. I did and tried to respond in the email it came back as not accepting responses.

    LP
    Laura P.
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 1 out of 5 stars
    3 months ago
    Knic

    Not good

    VM
    Vern M.
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief
  • Rated 5 out of 5 stars
    3 months ago
    Love these!

    The cotton boybriefs are my absolute favourite

    MM
    Maryam M.
    Verified Buyer
    Reviewing
    Super Leakproof® Cotton Boybrief

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