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New

Color: Warm Sand

Size:

Size:

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Home / Boyshort Underwear / Leakproof UltraThin No-Show Boybrief
New

Leakproof UltraThin No-Show Boybrief

$34.00 CAD

Mix & Match: 3+ for $25 each
Checkmark

Absorbs about 2.5 super tampons

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Invisible under clothes

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Moderate protection without the bulk

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Machine washable

| Black
| Black
| Black
| Black

Absorbency: Moderate
Drop
Drop
Drop
Drop
Drop

Color: Black

Size:

True to Size

•

Size:

Size and Fit Guide

Leakproof Underwear is Sales Tax Free in Canada*
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.

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.

Shipping Charges

Orders over $100* CAD = Free Shipping (2-6 business days)
Orders under $100* CAD = $12 CAD Shipping (1-3 business days)
Orders delivering to NWT, Nunavut and Yukon are subject to $20 delivery fee.
*After discounts, before shipping and taxes.
Easy Exchanges within 30 Days

Returns

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.

Return Policy

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

Sale & Last Call

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

Boybrief silhouette with a classic mid-rise fit and full bum coverage.

Worry-Free Protection

Our newest leakproof innovation provides more absorbency without the bulk. Patented 360 LeakSeal™ technology locks in leaks at every edge.

Moderate Absorbency

Absorbs 2.5 super tampons worth of liquid—perfect for moderate flow days, light bladder leaks, and sweat. The carbon cotton gusset top layer keeps you dry.

No-Show Style

Buttery-soft and smooth fabric gives a seamless look and feel. Disappears under clothes, even leggings.

Easy to Wash

Machine washable just like regular underwear.

Zoom

| Black
| Black
| Black
| Black

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
    6-11 tsp
  • pad
    about 1.5-3 regular pads
  • tampon
    about 3-6 super tampons
  • cup
    about 1-2 menstrual cups

Light

Drop
Drop
Drop
Drop
Drop
  • • light period days
  • • sweat
  • • sweat and 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 3-6 tsp
  • pad
    about 1-1.5 regular pads
  • tampon
    about 2-3 super tampons
  • cup
    about 0.5-1 menstrual cups

Ultra

Drop
Drop
Drop
Drop
Drop
  • • extra heavy period days
  • • overnight protection
  • • light bladder leaks
  • tsp
    13-17 tsp
  • pad
    3.5-4.5 regular pads
  • tampon
    7-9 super tampons
  • cup
    2-3 menstrual cups
FRESH FIX TECHNOLOGY®

Built-in protection that feels like nothing at all.

Our patented 360 LeakSeal™ technology locks in leaks at every edge. The ultra-thin liner absorbs about 2.5 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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4.7
Rated 4.7 out of 5 stars
Based on 23 reviews
Total 5 star reviews: 19 Total 4 star reviews: 1 Total 3 star reviews: 3 Total 2 star reviews: 0 Total 1 star reviews: 0
87%would recommend this product
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23 reviews
  • Rated 5 out of 5 stars
    3 minutes ago
    Great!

    I like these! 5’3”, ~125lbs, size small. Everything was perfect!

    Grace P.
    Verified Buyer
    Was this helpful?
  • Rated 3 out of 5 stars
    3 days ago
    Love the fit but not enough coverage in the front!

    I want to love these. The material is so thin and soft, and they are such a comfortable cut. But the gusset would need to come up another 2 inches in the front to prevent leakage. Please fix this knix!!! On all your underwear. If you move around at all, there is just not enough coverage in the front. I don't see how I can spend any more money on this underwear if this problem isn't addressed.

    Dione
    Verified Buyer
    Was this helpful?
  • Rated 3 out of 5 stars
    3 days ago
    Wish they had better coverage in the front but I love the fit.

    I really want to give these a 5 star review, but like all the knix underwear I have, they do not have enough coverage in the front. For me not to have leakage issues, the gusset would need to come about 2 inches more in the front. So frustrating because they are soooo comfortable, the fabric is so nice and soft and thin, but for leakproof underwear they are far from leakproof! Only work for me on light days.

    Dione
    Was this helpful?
  • Rated 3 out of 5 stars
    4 days ago
    Cut different from last order

    Like the colors but the cut is different than previous order. Doesn’t fit as well either.

    Judi M.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    1 week ago
    Leakproof panties

    Good fit

    Geraldine D.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    1 week ago
    Great pair of underwear

    Great pad for most of the month's non-period daily discharge. Good for backup coverage if my period cup leaks. Comfortable on the stomach and covers the bum. No panty lines.

    Faith C.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    2 weeks ago
    Great

    Love these as always

    Christina R.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    3 weeks ago
    Comfy

    Love them

    Sherry S.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    1 month ago
    Love 💕

    I love these soooooooo much .. it’s like you heard my silent wish for this style.. The dream shorts are awesome if you need all the absorbing power. But these lighter ones fit me so much better. Love love love .. thank you Knox 🙏🏽💕

    Allison G.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    1 month ago
    Best fit yet!

    Feel like normal underwear but with the security no leaks will show. The fit is my new favourite. I’ve had dream shorts, sleep boxers, ultra thin high rise and boy shorts, thigh savers and teen overnight shorts so I’ve tried them all!

    My bladder leak problem has also improved with some help so the boy briefs are perfect. I feel like a woman again in the new boy briefs!!!

    Heather F.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    1 month ago
    No Roll!

    I never liked boyshorts because they always rolled up - these ones do not! Stay in place. Seamless. Extremely comfortable to wear all day long! New favorite, highly recommend!

    Kim N.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    1 month ago
    The best!

    Very comfortable, fit well, true to suze

    Adriana L.
    Verified Buyer
    Was this helpful?