Pro Flex Trunk: Black
Pro Flex Trunk: Black
Pro Flex Trunk: Black
Pro Flex Trunk: Black
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Pro Flex Trunk

Black

Moisture-wicking mesh, offering breathable, anti-odor support.

$0.00 USD $26.00 USD
Size:

Size Guide
Color:  1 Color
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The Pro Trunk is engineered to move with minimal friction and complete comfort. These Trunks feature The Original 3D Pouch to ensure everything is separated and supported so you can always put your best foot forward.

The fabric is a breathable, moisture-wicking polyester blend mesh featuring Ionic+® anti-odor technology that does not wash out.

Fabric: 89% Recycled Polyester, 11% Spandex

The Original 3D Pouch
Breathable Mesh
Friction-free smooth finish
Ionic+® Anti-Odor Tech
Premium No-Roll Waistband
Chafe-Free Flatlock Stitching

Model shown is 6’0” tall, 175lbs, has a 32” waist and is wearing size medium.

This 3.5" inseam Trunk has a secure feeling fit.

View Size Guide


All BN3TH fabrics are soft and made from a performance stretch fabric. If your measurements are between sizes, select a larger size for a looser fit or a smaller size for a tighter fit.

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Free standard shipping is available on all orders above $75 (after discounts and before taxes).

All available shipping options will be visible at checkout. We ship orders within 1-2 business days, but this can increase during promotional periods.

We offer a 30-day return window for all purchases made directly through our website. To submit a return request, please use our online portal: returns.bn3th.com.

For more information, check out our Frequently Asked Questions page.

ENGINEERED COMFORT

WHY WE MADE THIS

The Pro Flex is all about keeping the sweat wicked, your form tight and the body feeling fresh. So go run, lift, climb, play…the Pro can tackle any workout without holding you back. And with Ionic+® anti-odor technology, you can focus on what matters most.

SUSTAINABILITY MATTERS

Made with post-consumer recycled polyester fabric and elastic, this product is certified to the Global Recycled Standard (GRS).
OEKO-TEX® certified fabrics guarantee that our end products are tested and proven free from harmful toxic chemicals.

Overall rating: 4.737003 / 5 from 327 reviews.

AI Generated Review Summary

The Pro Flex Trunk in Black is praised for its comfort, fit, and support, making it a top choice for workouts. Customers appreciate its breathable, moisture-wicking fabric and the innovative 3D Pouch design. While some find the fabric coarse, overall satisfaction with the material and design is high.

Summary topics

  • Fabric Comfort: 5%
  • Product Feel: 11%
  • Material Quality: 9%
  • Comfort and Fit: 4%
  • Support and Comfort: 7%

Review topics: ["size","fit","color","support","fabric","weight","quality","issues","material","look","feel","underwear","comfort","design","customer service","boxer briefs","style","boys","pouch","boxers","wear","brand","pair","briefs","trunks","work","waistband","undies","buy","undergarments"].

Review highlights

  • "Excellent fit, incredible comfort, soft material" — Rod C.
  • "Comfort, lightweight material, and fit are perfect." — Mark C.
  • "Excellent comfort, design, texture, durability, stretch ability." — CONNELL S.

Reviews

I like it

"On 5/28/2026, I ordered the then-new Pro Flex Boxer Brief in 3 colors. I was pleased to see that the exceptional build quality that I have come to expect from BN3TH is clearly evident. And the "breathable, moisture-wicking polyester mesh with Ionic+ anti-odor technology" seems to work very well here in the hot summer of Phoenix, Arizona, so I ordered 3 more. The bottom line is that I like it very much. However, I must say that for the winter half of the year, I prefer the somewhat thicker material (which is not mesh) of BN3TH’s Infinite Boxer Brief with "lonic No Stink" technology, which has sadly been discontinued."

— John P. (5/5)

Really nice

"Super comfy and fit great"

— Philip O. (5/5)

Comfortable support dor the twig and berries!

"I have worn BN3TH underwear for a few years now and as much as you can like a pair of underwear these are great. The support and comfort they provide is not really comparable to any other brand out there. I tried several different brands and the twig and berry comfort of the BN3TH is the best. No weird separator or fabric to rub you in the wrong places. Just a nice soft pouch for the boys to sit. I recommend them to any guy looking to get support and comfort all in one comfortable package."

— Mark S. (5/5)

Great buy:)

"My husband has gone on and on about these. This specific type is perfect for work! (Compared to the “icon” ones that are made of Tencel—which are more for everyday leisurely wear in his opinion). These are very durable and still very soft. They hold everything in place perfectly, as well ( —according to him). Anyway, we definitely recommend them lol. Please make some for females! Loungewear/ pajamas/loose fitting clothing - in the tencel material- would be amazingggg! Side note: My husband is roughly 225lbs, 5,10”-5,11”ish, wears a size 38 in most pants/ shorts, or XL in shorts not sized in numbers. He has ordered & bought probably 10+ pair of these, possibly more, and only ever bought size XL - and there always fit perfectly no matter which types he gets - so they are definitely true to size, for sure! (He always wears the boxer briefs). Hope this helps!:)"

— Matt’s :. (5/5)

10/10!

"My husband has gone on and on about these. This specific type is perfect for work! (Compared to the “icon” ones that are made of fencel—which are more for everyday leisurely wear in his opinion). These are very durable and still very soft. They hold everything in place perfectly, as well ( —according to him). Anyway, we definitely recommend them lol. Please make some for females! Loungewear/ pajamas/loose fitting clothing - in the tencel material- would be amazingggg! Side note: My husband is roughly 225lbs, 5,10”-5,11”ish, wears a size 38 in most pants/ shorts, or XL in shorts not sized in numbers. He has ordered & bought probably 10+ pair of these, possibly more, and only ever bought size XL - and there always fit perfectly no matter which types he gets - so they are definitely true to size, for sure! (He always wears the boxer briefs). Hope this helps!:)"

— Matt’s w. (5/5)

"Super comfortable and keeps things cool which is awesome"

— Sheridan (5/5)

Love them. Very comfortable

"Love them. Very comfortable"

— Bill N. (5/5)

Great feel, too tight

"I loved how the legs stayed put as I pulled on pants and avoided chafing. The material is great. But, they're too tight, so size up. I got a size Small because it said 30-32 and I wear a 29" in pants, but they're uncomfortably tight on the waist. 5'9" 130#."

— Paul M. (4/5)

Wear them anytime!

"Light weight material is an excellent undergarments. I use them for workout and all kinds of activities. Highly recommended two friends and anyone looking for readability and comfort."

— Michael H. (5/5)

Perfect fit and super comfortable

"Perfect fit and super comfortable"

— Jason B. (5/5)

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