Leakproof Underwear Bikini

Whether you’re training hard or just hanging out, these period undies protect you against sweat, discharge and leaks. A classic silhouette made from soft, stretchy, quick-drying fabric, you’ll have the comfort of maximum movement, and the confidence of reliable protection.

 

First layer: Wicks away sweat and moisture while neutralizing odors to keep you fresh all day long.

Second layer: A super thin, highly-absorbent liner that holds the power of 3 tampons or pads.

  

Key Features:

- Quick-Drying

- Moisture and Sweat Wicking

- Super soft & stretchy 

- Invisible under leggings or shorts (aka no visible seam lines)

- Patented leakproof technology

like your comfiest underwear, but with the power of 3 tampons.
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Holds about 3 tampons’ or pads’ worth of blood, sweat or discharge.
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Rapidly absorbs moisture to keep you fresh and dry all day.
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Thin, subtle, and designed to feel just like regular underwear.
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Simply care with mild detergent and machine wash on cold.

Whether you’re training hard or just hanging out, these period undies protect you against sweat, discharge and leaks. A classic silhouette made from soft, stretchy, quick-drying fabric, you’ll have the comfort of maximum movement, and the confidence of reliable protection.

 

First layer: Wicks away sweat and moisture while neutralizing odors to keep you fresh all day long.

Second layer: A super thin, highly-absorbent liner that holds the power of 3 tampons or pads.

  

Key Features:

- Quick-Drying

- Moisture and Sweat Wicking

- Super soft & stretchy 

- Invisible under leggings or shorts (aka no visible seam lines)

- Patented leakproof technology

Machine wash cold with mild detergent, do not bleach, lay flat to dry.


Body: 77% Nylon, 23% Xtra Life Lycra 

Lining: 86% Cotton, 10% Spandex, 4% Carbon 

Gusset: Fresh Fix Technology® 


Additional Product Ingredient Information

Because they’re, well, underwear, we can’t accept exchanges or returns on used items. BUT you can try your first pair on your first order risk-free for 30 days! Learn more about our First Pair Risk-Free Policy.


We offer free standard shipping on all orders over $70. We ship our items via DHL or Canada Post depending on your location. Please allow 1-2 business days for your items to be processed and shipped. During high volume periods, your order may take up to 7 business days to dispatch from our warehouse location.


US Orders: Please allow 3–10 business days for orders to arrive. 

International Orders: Please allow 10–25 business days for orders to arrive.  


NOTE: Orders placed on Friday after 1 PM will not be processed until the following Monday.   

CANADIAN CUSTOMERS: Shop www.knixteen.ca to order in Canadian currency.

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FOR THIS GENERATION
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for the planet!
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FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
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FOR THIS GENERATION
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for the planet!
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FOR THIS GENERATION
nothing is tmi here—we promise.
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All of our period underwear, swimwear, reusable pads, and activewear have our patented leakproof technology built right in.

First Layer: Wicks away sweat and moisture while neutralizing odors to keep your teen fresh all day long.

Second Layer: A super thin, highly absorbent liner that holds the power of 3–20 tampons or pads.

Third Layer: A secure, liquid-resistant outer layer keeps leaks from happening.

The short answer: nope! Depending on the absorbency level of the period underwear and the heaviness of your teens flow, your teen can wear our period undies on their own or as a backup to tampons or menstrual cups. They can wear our High and Super absorbency underwear alone and be totally protected, while our Medium absorbency underwear can be worn alone on lighter days or as backup on heavier days.

Step 1: Give your teens underwear a quick rinse under cold water.
Step 2: Throw it in the washing machine with your regular clothes. Wash on cold with mild detergent (no softener or bleach).
Step 3: There are two ways to dry them depending on the undies you have: lay flat to dry for medium absorbency products, or tumble dry on low for high to super absorbency products.
Step 4: That’s it! No ironing needed.

Check out our size chart here. If you want some help, we have virtual fitters ready on deck to help your teen find their perfect fit. Book a video call with them today.

Because they’re, well, underwear, we can’t accept exchanges or returns on used items. BUT your teen can try their first pair on your first order risk-free for 30 days!


If you ordered the wrong size of period underwear, we’ll send you a different pair at no cost or offer you a standard refund within 30 days of delivery (excluding original shipping fees).


If your order included multiple period underwear, open, wash, and wear one pair only. That way if you don’t love them, any unopened packages from the same purchase will be eligible for an exchange or standard refund (excluding original shipping fees).


All unopened packages will be donated to local organizations to support people in need.


Underwear purchased as part of the Period Party Sale is eligible for exchange or store credit only. No refunds. Sale items are not eligible for our First Pair Risk Free Policy.


Super Sleepover Shorts and Reusable Pads purchased as part of the Period Party Sale are final sale. No exchanges or refunds can be accommodated.

Super Absorbency

Absorbs 9–12 tsp (45–60 ml) of blood—that’s about 9–12 regular tampons or pads! Perfect for overnight protection or your teens heaviest days when changing into a fresh pair might not be convenient.


High Absorbency

Absorbs 4–8 tsp (20–40 ml) of blood, or the equivalent of 4–8 tampons or pads. These are perfect for heavy flow days.


Medium Absorbency

Absorbs up to 3 tsp (15 ml), or about 3 tampons or pads worth of blood. Ideal for light to medium flow days or as backup to tampons or period cups.

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Sustainable
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Absorbent
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Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Reviews
average rating 4.6 out of 5
Based on 373 reviews
  • 5 Stars
    298 Reviews
  • 4 Stars
    33 Reviews
  • 3 Stars
    13 Reviews
  • 2 Stars
    13 Reviews
  • 1 Star
    16 Reviews
90% of reviewers would recommend this product to a friend
Quality
Rated 4 out of 5
Comfort
Rated 4 out of 5
Sizing
Rated 0 on a scale of minus 2 to 2, where minus 2 is Fits Small, 0 is True to Size and 2 is Fits Large
Effectiveness
Rated 4 out of 5
Fit
Rated 0 on a scale of minus 2 to 2, where minus 2 is Runs Small, 0 is True to Size and 2 is Runs Large
373 Reviews
Reviewed by Deborah K.
Verified Buyer
I recommend this product
Rated 5 out of 5
Review posted

Knix

I love these because when I cough I don't have to worry about bladder leaks

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Reviewed by R. R.
Verified Buyer
I recommend this product
Rated 5 out of 5
Review posted

Love!

My girls love the Period underwear. It gives them more confidence because they are not worried about leaking at school. I ended up buying some for me and I love them as well!

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Reviewed by Rochelle P.
Verified Buyer
I recommend this product
I'm a...
Adult
I purchased for...
Myself
Pant Size
Teen 18-20
Size Purchased
L
Usage
  • Period
Rated 5 out of 5
Review posted

Leakproof

I absolutely loved them. I wore them at night and didn’t have any leaks.

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Quality
Rated 5 out of 5
Comfort
Rated 5 out of 5
Sizing
Rated -1 on a scale of minus 2 to 2, where minus 2 is Fits Small, 0 is True to Size and 2 is Fits Large
Effectiveness
Rated 5 out of 5
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Reviewed by Susan C.
Verified Buyer
I recommend this product
Rated 5 out of 5
Review posted

Teen leak proof underwear

Very well-made I am pleased with these items

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Reviewed by Carey S.
Verified Buyer
I recommend this product
I'm a...
Adult
I purchased for...
A Teenager/Tween
Pant Size
Teen 12-16
Size Purchased
M
Usage
  • Primary Protection
Rated 5 out of 5
Review posted

Fantastic for my teen

She wears them for dance and the bikini style works great. Even for ballet bodysuit and tights. Sleep shorts are a must!

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Quality
Rated 5 out of 5
Comfort
Rated 5 out of 5
Sizing
Rated -1 on a scale of minus 2 to 2, where minus 2 is Fits Small, 0 is True to Size and 2 is Fits Large
Effectiveness
Rated 5 out of 5
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