Classic Bikini

£27.95
Bikini - Heavy Absorbency

Wear on Heavy days

holds 4 tampons' worth

  • Wear for up to 12 hours on heavy days
  • Holds four tampons' worth or 20/25ml
  • For periods, leaks & incontinence 
  • Great for day and night.
  • OEKO-Tex certified materials

Buy more + save more.

Classic Bikini

Wear on Heavy days

holds 4 tampons' worth / 20-25ml

£27.95

  • Wear for up to 12 hours on heavy days
  • Holds four tampons' worth or 20-25ml
  • For periods, leaks & incontinence 
  • Great for day and night.
  • OEKO-Tex certified materials

Buy more + save more.

Style + fit

Made with soft 'n' sustainable eco-friendly TENCEL modal fabric and featuring a soft and stretchy lace waistband. 


The super absorbent gusset keeps you protected all day.

Fabric + care

Inner and Outer: 95% TENCEL Modal 5% Elastane, Trim: 100% Polyester, Gusset: Absorbent blend, Breathable PUL


Care: Quick rinse 🚿 40 degree wash 👌🏽 Hang to dry ✌🏿 No bleach or fabric softener ⚠️

Sustainably sourced

Fast + free UK shipping

Ethically manufactured

We give to girls in need

Customer Reviews

Based on 110 reviews
85%
(94)
11%
(12)
4%
(4)
0%
(0)
0%
(0)
S
S.
Flow: Super Heavy
Products used: FLUX Undies, obvs!, Disposable pads
Definitely experiencing more comfortable periods
H
H.L.
Flow: Heavy, Moderate
Products used: FLUX Undies, obvs!, Cloth pads
My Favourite Period Pants
J
J.
Flow: Heavy
Products used: FLUX Undies, obvs!, Disposable pads
A very absorbent comfortable bikini
J
J.
Flow: Heavy, Moderate
Products used: FLUX Undies, obvs!
Great product
  • How They Work
  • Money-Back Guarantee
  • Find Your Size
  • FAQ's

Moisture-wicking

Soft material wicks moisture and dries fast

Anti-microbial

Prevents bacteria building up and keeps smells away

Super absorbent

Absorbs liquid without feeling bulky or heavy

Leak-proof

Breathable layer prevents leaks and stains

Moisture-wicking

Soft material draws moisture away and dries fast

Anti-microbial

Prevents bacteria building up and keeps smells away

Super absorbent

Absorbs moisture and liquid without feeling heavy or bulky

Leak-proof

Breathable layer prevents leaks and stains all day

try our period-proof undies risk-free

if you're not period-ing better within 60 days, we'll give you your money back. no questions asked.

  • XXS
  • XS
  • S
  • M
  • L
  • XL
  • 2XL
  • 3XL
  • 4XL

size XXS

UK 4/6   US 0/2   EU 32/34

waist 60-64cm

hips 80-86cm

size XS

UK 8   US 6   EU 36

waist 65-69cm

hips 87-92cm

size S

UK 10   US 6   EU 38

waist 70-74cm

hips 92-97cm

size M

UK 12   US 8  EU 40

waist 75-79cm

hips 98-102cm

size L

UK 14   US 10   EU 42

waist 80-84cm

hips 103-108cm

size XL

UK 16/18   US 12/14   EU 44/46

waist 85-95cm

hips 108-118cm

size 2XL

UK 20/22   US 16/18   EU 48/50

waist 96-105cm

hips 119-129cm

size 3XL

UK 24/26   US 20/22   EU 52/54

waist 106-115cm

hips 130-140cm

size 4XL

UK 28/30   US 24/26   EU 54/56

waist 116-125cm

hips 141-145cm

what is your return policy?

We offer free returns and exchanges within 60 days of purchase, no questions asked! Just visit our Return & Exchange Centre to get started.

how long can i wear them?

If cared for properly, our undies are likely to have a maximum tech performance of approximately 3 years. This means washing them on a 30-40 degree wash with the rest of your delicates, never using bleach or fabric softener, and hang drying! In terms of length of wear, we measure our undies by absorbency with our highest absorbency styles holding 4 tampons worth of fluid. For some customers, that means wearing them the whole day and for others that may mean carrying an extra pair of FLUX Undies as a backup. 

how do they work?

FLUX Undies are underwear that absorbs your period. Every pair is made with technology that absorbs your flow, wicks moisture, controls odour, and prevents leaks — leaving you fresh and dry. Take a look at our How it Works page to learn more.

how do i find the right size?

We recommend following the hip measurement, as most of our styles sit on the hips. Be sure to measure your hips at their widest point to find the most accurate size for you! In case you don't have a tape measure, you can use the size you usually are most comfortable with for your underwear. We recommend the undies fit snuggly, but not so tight that it's uncomfortable. For reference, you can check out our size chart above.

Why not try some other styles...

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