Leakproof UltraThin No-Show Underwear Bikini

Hanging out or running to your next class? These period undies provide the ultimate comfort you want, plus ultra-thin protection you need from sweat, discharge and leaks. It’s a classic silhouette made with a super soft-and-stretchy, quick-drying material. It absorbs about the equivalent of 2.5 super tampons for an extra dose of confidence on those medium-flow days.

Key Features:
- 360LeakSeal™ patented technology designed to seal in leaks from every angle
- Soft and stretchy for comfort throughout the day
- Seamless look for any OOTD
- Quick dry for that fresh feel

more absorbent protection, without any extra bulk
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Holds about 2.5 super tampons' worth of blood.
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Rapidly absorbs moisture to keep you fresh and dry all day.
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Allows air to circulate to keep you cool and dry.

Hanging out or running to your next class? These period undies provide the ultimate comfort you want, plus ultra-thin protection you need from sweat, discharge and leaks. It’s a classic silhouette made with a super soft-and-stretchy, quick-drying material. It absorbs about the equivalent of 2.5 super tampons for an extra dose of confidence on those medium-flow days.

Key Features:
- 360LeakSeal™ patented technology designed to seal in leaks from every angle
- Soft and stretchy for comfort throughout the day
- Seamless look for any OOTD
- Quick dry for that fresh feel

Machine wash cold, do not bleach, do not iron, do not dry clean, lay flat to dry.

Body: 77% Nylon, 23% LYCRA® XTRA LIFE™Spandex;

Fresh Fix Technology®Gusset: Gusset 1: 86% Cotton, 10% Spandex, 4% Carbon; Gusset 2: 96% Polyester, 4% Spandex; Gusset 3: 83% Polyester, 11% Spandex, 6% Polyurethane

Additional Product Ingredient Information

For items with a 20% or more discount, you may exchange for another item or return for store credit. No refunds can be accommodated. 

Items marked as “Flash Sale” or “Clearance” are final sale, meaning no returns, exchanges or refunds can be accommodated. No exceptions. 

Please note: Sale items are not eligible for 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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nothing is tmi here—we promise.
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Heavy Absorbency

Absorbs about the same as 3 super tampons. Perfect for overnight protection or your teens heaviest days when changing into a fresh pair might not be convenient.


Moderate Absorbency

Absorbs about 2.5 super tampons' worth of blood. Ideal for medium period days, discharge and sweat.


Light Absorbency

Absorbs about the same as about 1 regular tampon worth of blood, sweat or discharge. Ideal for lightest period days, spotting, sweat and discharge.

Each pair has a built-in liner that absorbs period blood. Kt Period Underwear is categorized by light, moderate and heavy flows so you can find the right pair for your teen’s needs.

All of our period underwear, swimwear, reusable pads, and activewear have our patented leakproof technology built right in. Liner’s are discreet and comfortable, and fit for your teen’s unique flow. 

That’s up to your teen or tween! Every flow and comfort level is different.

Depending on the absorbency level of the period underwear and the heaviness of your teen’s flow, they can wear our period undies on their own or as a backup to tampons or menstrual cups. 

We always recommend they choose an option that makes them feel most confident!

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.

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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 4.8 out of 5
Based on 10 reviews
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90% of reviewers would recommend this product to a friend
Quality
Rated 4 out of 5
Comfort
Rated 5 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
Write a Review
Review posted
Reviewed by Dollface4681 S.
Verified Buyer
Height
<5’5”
Usual Pant Size - Knixteen
Womens 4-8
Size Purchased - Knixteen Underwear
M
Rated 5 out of 5

Peace of mind

My daughter has been exclusively wearing Knix Teen underwear for over a year now and she refuses to wear anything else. Comfortable and give her (and I) peace of mind.

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I recommend this product
Comfort
Rated 5 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
Effectiveness
Rated 4 out of 5
Ease of Use
Rated 5 out of 5
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Review posted
Reviewed by Rebecca C.
Verified Buyer
Pant Size
Teen 00-2
Size Purchased
S
Rated 5 out of 5

Amazing

Perfect for my teen daughter who plays sports She is a size 0 in pants and the size small fit perfect

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I recommend this product
Quality
Rated 5 out of 5
Comfort
Rated 5 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 5 out of 5
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Review posted
Reviewed by CT M.
Verified Buyer
Rated 5 out of 5

Be aware of the amount of your flow

This is low profile, so you need to watch for your flow. Doesn’t last as long as some other period undies, but the positive trade off is that it is not being bulky. My teen far prefers this to the slightly bulkier ones.

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I recommend this product
Comfort
Rated 5 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
Effectiveness
Rated 4 out of 5
Ease of Use
Rated 5 out of 5
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Review posted
Reviewed by Sandra C.
Verified Buyer
I'm a...
Parental Figure
I purchased for...
A Teenager/Tween
Pant Size
Teen 00-2
Size Purchased
XS
Usage
  • Primary Protection
Rated 5 out of 5

Revolutionary Feminine Protection

KT by Knix period underwear has been an absolute game-changer for my teen! As a dancer, she needs to feel confident and comfortable while performing, and traditional pads and liners just weren’t cutting it—they were bulky, uncomfortable, and constantly shifting. I started looking for alternatives and came across KT by Knix. After ordering a couple of pairs to try, she was immediately sold!

These are true to size, super comfortable, incredibly absorbent, and most importantly—completely leakproof. Whether she’s at practice, in class, or on stage, she can focus on dancing without worrying about leaks or discomfort. The confidence and peace of mind these provide are priceless! I highly recommend them to any parent looking for a reliable and comfortable period solution for their active teen.

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I recommend this product
Quality
Rated 5 out of 5
Comfort
Rated 5 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 5 out of 5
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Review posted
Reviewed by Sarvia B.
Verified Buyer
Pant Size
Kids 12-14
Size Purchased
XS
Usage
  • Primary Protection
Rated 5 out of 5

Great underwear

I have two girls that play sports and these are perfect for them. They don’t complain of any discomfort and best part…they wash very well! Highly recommend this product

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I recommend this product
Quality
Rated 5 out of 5
Comfort
Rated 5 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 5 out of 5
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