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Leakproof UltraThin No-Show Bikini
#1 Daytime Solution
Leakproof UltraThin No-Show Bikini
$27.00
USD
Buy 3+ Save 15%, Buy 5+ Save 20%
Absorbs about 2.5 super tampons
Invisible under clothes
Moderate protection without the bulk
Machine washable
Size and Fit Guide
How to Measure
In order to select the correct sizing, we recommend you take the following measurements using a soft tape measure. If necessary, ask someone else to help.
Waist
Measure around the narrowest part of your torso, usually just above your belly button. Keep the tape snug and level, but not tight. The number where it meets is your waist measurement.
Hip
Stand with your feet together and measure around the fullest part of your hips and buttocks. Keep the tape level and snug, but not tight. The number where it meets is your hip measurement.
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Leakproof UltraThin No-Show Bikini
Leakproof UltraThin No-Show Bikini
Leakproof UltraThin No-Show Bikini
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Product Description
Comfort-First Fit
Bikini silhouette with a classic mid-rise fit, medium hip and 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 your regular underwear.
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How to Choose?
Essential
- • Days you don’t need leak protection. Everyday freshness and moisture wicking.
-
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.
-
about 8-14 tsp
-
about 1.5-3 regular pads
-
about 4-7 super tampons
-
about 1.5-3 menstrual cups
Light
- • Daily freshness. For sweat, discharge, period spotting, or backup protection.
-
about 1-3 tsp
-
about 1-3 pantyliners
-
about 1-3 regular tampons
-
about 0.5 menstrual cups
Moderate
- • For mid-cycle flow, surprise cough or sneeze leaks, or a really sweaty spin class.
-
about 4-8 tsp
-
about 1-1.5 regular pads
-
about 2-4 super tampons
-
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.
-
about 15-20 tsp
-
about 1.5-2.5 super pads
-
about 7-11 super tampons
-
about 2-3 menstrual cups
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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
Middle Layer
Leakproof Layer
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How to wash
Knix underwear is 100% reusable and machine washable, just like your regular undies.
Not required. But for best results, you can rinse your leakproof with cold water in the tub or sink before washing.
Machine wash on a cold, gentle cycle with mild detergent.
For their longest life, air drying is best. Hang or lay flat to dry.
Fabric softeners, bleach, ironing, or heat from the dryer.
Total 5 star reviews: 507 Total 4 star reviews: 83 Total 3 star reviews: 46 Total 2 star reviews: 32 Total 1 star reviews: 42
What our customers are saying
Generated by AI from 100 most recent customer reviews
Last updated 2 months ago
Customers say these period underwear are comfortable and provide excellent protection without the bulkiness of traditional pads. Many appreciate the thin, no-show design that works well under clothing and the stylish patterns like polka dots. Users frequently mention the confidence and peace of mind these provide during periods, workouts, and daily activities. Several note they're particularly good for teens and lighter flow days. However, common concerns include sizing inconsistencies, with many finding recent purchases run smaller than expected. Some mention the front coverage could be longer, and a few experience issues with leg holes being too tight. Despite sizing challenges, most customers praise the comfort, absorbency, and quality of the product.
85%would recommend these products
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How do you use your Leakproof?
Usual Pant Size
710 reviews
- Rated 5 out of 5 stars4 minutes ago5 Stars
Super comfortable and secure 10/10
KaitlynReviewingLeakproof UltraThin No-Show Bikini Kit* - Rated 2 out of 5 stars16 hours ago2 Stars
The seam started to unglue and come apart after one wear!
LizReviewingLeakproof UltraThin No-Show Bikini - Last Call - Rated 4 out of 5 starsYesterdayLove! But…
These are as advertised and I love them for tampon backup or sweat. I prefer the “light leakproof” for single coverage because the liner goes a little higher in the front. With these, the liner stops just under where I need it to for spotting or periods. Yes, I recommend these but consider how much front coverage you need if buying for spotting or periods.
KKnixYesterdayHey Cristine,
Thanks for the detailed feedback! We're so happy you love them for backup and sweat protection. We really appreciate you sharing the coverage tip to help other customers find their perfect fit!
Team Knix
Cristine C.Verified BuyerReviewingLeakproof UltraThin No-Show Bikini - Rated 5 out of 5 stars2 days agoWorth every penny
Much more comfortable than a panty liner
KKnix2 days agoHey Gary!
Thanks so much for taking the time to review our Leakproof UltraThin No-Show Bikini! We're thrilled to hear you're loving the comfort over traditional options.
Team Knix
Gary C.Verified BuyerReviewingLeakproof UltraThin No-Show Bikini - Rated 5 out of 5 stars3 days agoPerfect
Wear to Pilates all
The time best panties ever !
KKnix3 days agoHey Jess!
This is amazing! We're so happy our Leakproof UltraThin No-Show Bikini is your go-to for Pilates. Thanks for making us your workout partner!
Team Knix
Jess W.Verified BuyerReviewingLeakproof UltraThin No-Show Bikini - Rated 5 out of 5 stars6 days agoMore Colors!
I love these moderate leak underwear; they're absolutely perfect for the bookend days of my period, and I love that they keep coming out with new patterns and colors! :)
KKnix6 days agoHey Lisa!
This is amazing! We're so happy you're loving the Leakproof UltraThin No-Show Bikini for those bookend days. We love bringing you new patterns and colors too! 💖
Team Knix
Lisa A.Verified BuyerReviewingLeakproof UltraThin No-Show Bikini - Rated 5 out of 5 stars1 week agoComfy fit
Love the polka dot pattern.
KKnix1 week agoHey Lisa!
Thanks so much for the review! We're thrilled you're loving the comfy fit and polka dot pattern on your UltraThin No-Show Bikini!
Team Knix
Lisa R.Verified BuyerReviewingLeakproof UltraThin No-Show Bikini - Rated 5 out of 5 stars1 week agoSo confortable
Very confortable and leak proof
KKnix1 week agoHey Clara!
Thanks so much for taking the time to review our Leakproof UltraThin No-Show Bikini! We're so happy to hear you're loving the comfort and protection!
Team Knix
Clara F.Verified BuyerReviewingLeakproof UltraThin No-Show Bikini - Rated 5 out of 5 stars1 week agoJe ne porte plus que ça
Depuis que je les ai essayées, ce sont les seuls sous vêtements que je porte. J’ai du m’ajuster pour la taille car après avoir été portées quelques fois, les culottes ont tendance à étirer. J’ai dû prendre une taille en-dessous de ce que je porte dans les autres marques.
Jacinthe L.Verified BuyerReviewingPOS - Leakproof UltraThin No-Show Bikini - Rated 5 out of 5 stars1 week agoGreat
Works and comfy
KKnix1 week agoHey Tracy!
Thanks so much for taking the time to review our Leakproof UltraThin No-Show Bikini! We're so happy to hear you're loving the comfort and performance!
Team Knix
Tracy F.Verified BuyerReviewingLeakproof UltraThin No-Show Bikini - Rated 5 out of 5 stars1 week agoLove
So good, comfy and wash so well
KKnix1 week agoHey Kenneth!
Thanks so much for taking the time to review our Leakproof UltraThin No-Show Bikini! We're so happy to hear you're loving the comfort and how well they wash!
Team Knix
Kenneth M.Verified BuyerReviewingLeakproof UltraThin No-Show Bikini - Rated 5 out of 5 stars1 week agoMust buy
These undies exceeded expectation. They fit true to size and are genuinely comfortable. I have tried other period underwear brands and have found them all very uncomfortable and oddly tight around the legs. These fit like normal underwear. 10/10 recommend
KKnix1 week agoHey Rachel!
This is amazing! We're so happy our UltraThin No-Show Bikini exceeded your expectations and feels like normal underwear. There's nothing better than hearing our customers feel comfortable in their Knix!
Team Knix
Rachel G.Verified BuyerReviewingLeakproof UltraThin No-Show Bikini
