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Home / Boyshort Underwear / Leakproof UltraThin No-Show Boybrief

Leakproof UltraThin No-Show Boybrief

$34.00 USD

Mix & Match: 3+ for $25 each
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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

| Cosmic
| Cosmic
| Cosmic
| Cosmic
| Cosmic
| Cosmic
| Cosmic

Absorbency: Moderate

Moderate
Drop
Drop
Drop
Drop
Drop
about 2-4 super tampons
Ultra
Drop
Drop
Drop
Drop
Drop
about 7-11 super tampons

Color: Cosmic Limited Edition

Size:

True to Size

•

Size:

Size and Fit Guide

Get FREE Express Shipping on all orders $125+

Shipping

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.

Shipping Charges
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

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

Mid-rise boybrief silhouette with full bum coverage for a smooth, comfortable fit.

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

Made from our signature buttery soft fabric with a wide, comfortable waistband. Wear it on its own or under your favorite pajamas.

Easy to Wash

Machine washable just like regular underwear.

Zoom

| Cosmic
| Cosmic
| Cosmic
| Cosmic
| Cosmic
| Cosmic
| Cosmic

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.

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 61 reviews
Total 5 star reviews: 52 Total 4 star reviews: 4 Total 3 star reviews: 3 Total 2 star reviews: 2 Total 1 star reviews: 0
92%would recommend this product
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61 reviews
  • Rated 5 out of 5 stars
    4 minutes ago
    No Show Boy-brief

    ⭐⭐⭐⭐⭐

    Bronwen W.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    2 hours ago
    5 Stars

    Great fit and protection!

    Susan
    Was this helpful?
  • Rated 5 out of 5 stars
    10 hours ago
    Worry proof comfort

    Being a senior lady, I needed something comfortable & reliable for leaks. These are amazing & fit the requirements. So glad I found knix!

    Susan G.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    Yesterday
    Best Fit

    I love how Boybriefs fit. They've been my favorite for several years and the Leakproof Ultra Thin No-Show is a real plus for comfort and confidence. Thanks KNIX.

    Ann L.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    Yesterday
    Best undies!

    Excellent fit

    Comfortable

    Wears well

    Sandra C.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    2 days ago
    Love these

    No panty lines changes the game on what I can wear that time of the month. Such a life saver!

    Rachel E.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    4 days ago
    My favorite fit

    Love these they are so comfortable.

    Susan W.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    4 days ago
    Keep ordering

    Love thaws so much rhat I keep ordering

    Tamara L.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    4 days ago
    My purchases feedback

    I couldn’t be happier with my purchases! What a treat to wear the bras and the panties that are SO comfortable!! Thrilled that they dry overnight after laundering!! Thank you!!

    Jennifer S.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    1 week ago
    My new go-to panties.

    Very comfortable! They fit perfectly and there are no panty lines - even under my workout leggings.

    Michelle C.
    Verified Buyer
    Was this helpful?
  • Rated 5 out of 5 stars
    1 week ago
    Boybrief

    These are my favourite style of underwear. Comfortable and fit perfectly.

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

    Amazing

    Ive been wearing knix regular brief but absolutely love these so stocking up. Im runnng out of lingerie drawer space! Please make mire colors

    Carole
    Was this helpful?