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Flex Boxer

Adaptive support boxer for everyday movement. Flex uses a lightweight, high-stretch fabric that moves with your body while keeping KING's built-in-support system in place.

$38
$38
Sale Sold out
Size
Color Black

Size & Fit

Waist Hips
XS 24–26" 30–32"
S 28–30" 34–36"
M 32–34" 38–40"
L 36–38" 42–44"
XL 40-42" 46–48"
XXL 44-46" 50-52"

Shipping & Returns

US Shipping
Free over $50, otherwise $8. Arrives in 3–5 business days, or 1–2 with Express ($24). Orders ship within 1–2 business days.

International
Duties and taxes are covered, so there's nothing extra to pay at your door. Arrives in about 5–10 business days.

$15, free over $110: Canada, UK, Australia, New Zealand, Singapore, South Korea, Germany, France, Spain, Italy, Netherlands, Austria, Belgium, Czechia, Poland

$20, free over $150: Ireland, Portugal, Greece, Denmark, Sweden, Finland, Hungary, Croatia, Romania, Bulgaria, Slovenia, Slovakia, Estonia, Latvia, Lithuania, Luxembourg, Japan, Hong Kong, Mexico, Israel

Everywhere else: Rates are calculated at checkout, and duties may be collected on delivery.

Returns
All sales are final, since it's underwear. If something's wrong (a defect, a missing item, or the wrong item sent), email admin@kingsonly.co and we'll make it right.

Materials & Transparency

88% Recycled Polyester, 12% Elastane

View full details
Let's compare our BDE

A guide to our support system.

  • Coming soon
Fabric

  • HardWear

    Technical Performance Knit

    Moisture Wicking + Quick-Dry

  • FlexWear

    Adaptive Stretch Knit

    Lightweight + Highly Flexible

  • SoftWear

    Premium Cotton Blend

    Breathable + Naturally Soft

Feel
  • Structured
  • Adaptive
  • Relaxed
Compression level
What customers say

Best for:

  • Training

    Running

    High-output days

    When you need to go hard.

  • Everyday wear

    Walking + travel

    Working

    Days that require a little more flexibility.

  • Recovery days

    Lounging + sleeping

    Low-impact days

    Sundays.

Benefits

Ball Support

Thermal Regulation

Butt Lift

Anatomical Fit

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KingSling

An anatomical support pouch engineered directly into the fabric. Built to hold everything in place.

Starting at

FAQ

For more questions here

ASK US A QUESTION

What makes FLEX different?

FLEX has the same KingSling™ support as HARD, but with a more flexible, lightweight feel. It lifts, separates, and stabilizes without feeling restrictive.

When should I wear FLEX?

Everyday. Work, walking, travel, going out, or anywhere your day takes you. FLEX is built to move with you.

What does FLEX feel like?

Lightweight, soft, and flexible. You get the support you want without the locked-in feeling of a more structured boxer.

How is FLEX different from HARD?

Both feature the KingSling™ for the same core support. HARD has a more structured, compressive feel. FLEX has more stretch and flexibility for everyday movement.

Does FLEX actually support your balls?

Yes. That's the point. The KingSling™ lifts, separates, and stabilizes everything so your balls aren't just hanging around down there.

Will I have to adjust myself throughout the day?

That's what the KingSling™ is designed to prevent. It keeps everything supported and in place without constant pulling, shifting, or readjusting.

What are the care instructions?

Machine wash cold with like colors. Do not bleach. Air dry flat. Cool iron if needed. Do not dry clean.

Why is KING different from other underwear brands?

Most underwear is designed to hold everything in place. We designed KING to actually support it. Every pair is built around the anatomy of the guy wearing it—because your balls deserve better than an afterthought.

ASK US A QUESTION