Product Colors and Sizes

  • Black Friday product
  • New Deal product
  • Cyber Monday product
  • Clearance product
  • Deal product
  • Best Seller product
  • Ecodesign product
  • New product
  • Staff Pick product
  • In The News product
  • Innovation product
  • product

900 B-Fast Swimming Trunks

Sale price: $10.00 Regular price: $19.99

Men's trunk-style swimwear, designed using the best fabric to ensure excellent chlorine-resistance and optimal comfort.

Color: Select a color
Size: Select a size
Size Guide

This product runs small

Sale price: $10.00 Regular price: $19.99

Free shipping over $35

Final Sale: No returns or exchanges

Free returns

Free pickup

San Francisco, 735 Market St. Options

Select an available color and size to see options.

Model: 8648322

Product Videos

Product Features

A photo of the 900 B-Fast Swimming Trunks in use

900 B-Fast Swimming Trunks | Our design teams have developed these briefs for the swimmer looking for a classic shape and who needs support.

Men's trunk-style swimwear, designed using the best fabric to ensure excellent chlorine-resistance and optimal comfort.

Chlorine resistant

more than 200 hours of use: recommended for regular use.


Swim trunks provide good support


Easy to adjust around waist using drawstring and a special silicon toggle.

Product Customer Reviews

Skip to reviews
270 Reviews
Write a Review 

900 B-Fast Swimming Trunks,black
Filtered by reviews Loading reviews…
Swim wear

Great fit and looks great on a fit body

icon-circle-checkmark verified purchase



Thank you for taking the time to write to us about your product experience. We truly appreciate your feedback.

Thanks & Regards,

Decathlon Brampton Team


Great value for money and I wear under my wetsuit.. my last pair lasted a few years so expect these to do the same. All good so far

icon-circle-checkmark verified purchase
Just right for swimming

Perfect tight fit, fabric in good quality. Comfortable to wear in water

icon-circle-checkmark verified purchase

The product is good, just that the size chart and actual product do not match

icon-circle-checkmark verified purchase
Running n Swimming

It's great for both running and swimming

icon-circle-checkmark verified purchase

พี่ชายชอบมากค่ะ ใส่สบายดี

สวัสดีค่ะ คุณ Prem



Pimpila K


ใส่สบายไม่อึดอัด รู้สึกคล่องตัว

สวัสดีค่ะ คุณวิศรุต



Pimpila K



icon-circle-checkmark verified purchase


Благодарим Ви, за отделеното време да споделите обратната си връзка за нашия продукт !

Като спортна компания, която се стреми да направи спорта достъпен за всеки, нашата цел е винаги да предоставяме качествени и функционални продукти.

Спортни поздрави,

Екипът на Декатлон България


Покриха очакванията ми и това което търсих

icon-circle-checkmark verified purchase


Мисията на Декатлон ще остане непроменена - да правим спорта достъпен за възможно най-много хора, по един отговорен към природата начин.

Благодарим Ви, че оценихте нашия продукт!

Спортни поздрави,

Екипът на Декатлон България

Velikost neodpovídá

Velikost neodpovídá...možná je to chlapecké M, ale dle označení pánské.

icon-circle-checkmark verified purchase

Dobrý den, 

děkujeme za Váš čas věnovaný recenzi tohoto produktu. Každá zkušenost je velmi cenná a pomáhá nám s vývojem nových modelů.

Chápeme, že ne každý produkt vyhovuje všem naším zákazníkům. Z těchto důvodů máte vždy 90denní bezplatnou lhůtu na vrácení pouze vyzkoušeného zboží. 

Za způsobené komplikace se velice omlouváme.

S láskou ke sportu



Sedí dobře,jen odolnost se prověří sama časem. Byl jsem jen jednou na bazénu.

icon-circle-checkmark verified purchase

Moje úplně první zkušenost se slipovými plavkami a jsou skvělé. Skvele se v nich plave. Pevně drží obsah plavek, což je mi příjemné. Jen se špatně šňůrka rozvazuje, když se zamotá, protože je tenoučká.

icon-circle-checkmark verified purchase
Tabell stimmt nicht

Badehose wäre super ist aber Mega eng . Die Grössen Tabelle stimmt nicht hätte lieber 1 nummer grösser genommen . Sonst super für den Preis

icon-circle-checkmark verified purchase
Falsche Grössen

Ich hatte zwei unterschiedliche Badehosen zur Abholung in der Filiale bestellt, Grösse L bzw. XL laut Decathlon Grössentabelle (gemäss Taillenumfang). Geliefert wurden die Grössen M bzw. M-L. Rücknahme und Erstattung in der Filiale erfolgten anstandslos. Die eine Badehose (Nabaiji 900) war in der Filiale in der passenden Grösse jedoch vorrätig. Qualität, Möglichkeit der Filialabholung, Umtauschmöglichkeit, Hilfsbereitschaft des Personals etc. alles einwandfrei. Aber der Versand einer falschen Grösse und dies gleich doppelt, sollte nicht möglich sein. Dafür ein Stern Abzug.

icon-circle-checkmark verified purchase
Passt gut

Alles gut

icon-circle-checkmark verified purchase
Skip to reviews

Size Guide

Size Guide Visual

Additional Product Information


Main fabric: 78.0% Polyethylene Terephtalate, 22.0% Elastolefin ; Lining: 100.0% Polyamide


Swimming trunks – side height 3.1”Swimwear should prioritize comfort. It should enable you to move with ease. That is why it is important to choose the shape of your swimwear carefully.The swimming trunks have a classic and timeless cut, providing great freedom of movement, as well as plenty of support.Details are positioned so that they mold to your body shape.


22%- Elastolefin 78% - PolyesterOur engineers have developed a polyester-based fabric and replaced the spandex fibers with fibers that give it sufficient elasticity to ensure user comfort while protecting it against the damaging effects of chlorine. This thread also offers the following benefits:- quick drying. - only loses 3 to 4% resistance throughout its lifespan.- UV-resistance: Colors are more stable.

Aquaresist technology

Products bearing the AQUARESIST label are guaranteed to deliver chlorine-resistance throughout their lifespan. They will keep their elasticity and be resistant to light. For these reasons, they are recommended for regular or intensive pool use.

Determining the environmental impact of our products

The environmental impact of the product is calculated over its entire lifecycle using different indicators. An ABCDE score is provided to enable easy identification of the most environmentally-friendly products when comparing products of the same type (T-shirts, pants, backpacks).Decathlon chose to apply this voluntary environmental labeling system.Web: Sustainability.decathlon.comVideo:

Product testing

Products labeled with AQUARESIST certification are tested under repeated cyclical loading in a pool of chlorinated water for more than 200 hours. No deterioration of elastic strength was observed throughout the test. Unlike a standard swimming product, the product remains intact.

Storage instructions

Store the swim shorts in a dry place.





Superior quality. Unbeatable prices.

For 40 years, Decathlon has delivered the best value in the retail sports industry by offering high-quality, sustainable and cost-effective products.

Decathlon makes the difference
  1. product-research

    Research and development

    delivers high-quality cost-effective products

  2. State-of-the-art production processes

    minimize manufacturing costs

  3. Optimized supply chain

    reduces retail prices

  4. laptop-checkout

    Minimal retail footprint

    lowers overhead and indirect costs


Size Guide Visual