10,000+ pairs sold·Free shipping on all orders·30-day fit guarantee·OEKO-TEX® certified·No synthetic chemicals·Ships same day·TENCEL™ Modal fiber·10,000+ pairs sold·Free shipping on all orders·30-day fit guarantee·OEKO-TEX® certified·No synthetic chemicals·Ships same day·TENCEL™ Modal fiber·
Foundation Brieffrom $22

The closest thing
to nothing.

Precision-knit from TENCEL™ Modal. Cooler than cotton, softer than silk, tuned at the fiber level to disappear on skin.

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From $22 · Free shipping · 30-day fit guarantee

★★★★★4.9 · 10,000+ men switched from cotton
Foundation Brief
★★★★★"I bought one pair. Threw out everything else I owned after day two."Marcus R.
★★★★★"My fertility doctor said ditch synthetic underwear. ANDROS was the only switch that actually lasted."Chad P.
★★★★★"Train twice a day. Zero chafing, zero overheating. Everything stays exactly where it should."Austin L.
★★★★★"First brand my husband ever asked me to reorder. Three months in a row."Sarah M.
★★★★★"I was skeptical. 48 hours later I ordered three more sets."James K.
★★★★★"Switched after learning about synthetic heat and hormone disruption. Felt the difference in a week."Jay T.
★★★★★"OEKO-TEX certified, no toxic dyes, TENCEL Modal. I did the research. ANDROS won by a mile."Nick S.
★★★★★"Size up, but genuinely the most comfortable thing I've worn in 30 years."Dillon W.
★★★★★"I bought one pair. Threw out everything else I owned after day two."Marcus R.
★★★★★"My fertility doctor said ditch synthetic underwear. ANDROS was the only switch that actually lasted."Chad P.
★★★★★"Train twice a day. Zero chafing, zero overheating. Everything stays exactly where it should."Austin L.
★★★★★"First brand my husband ever asked me to reorder. Three months in a row."Sarah M.
★★★★★"I was skeptical. 48 hours later I ordered three more sets."James K.
★★★★★"Switched after learning about synthetic heat and hormone disruption. Felt the difference in a week."Jay T.
★★★★★"OEKO-TEX certified, no toxic dyes, TENCEL Modal. I did the research. ANDROS won by a mile."Nick S.
★★★★★"Size up, but genuinely the most comfortable thing I've worn in 30 years."Dillon W.
Foundation Brief
Bundle
Most Popular
3 Set
$66$34$27.20
Save $38.80 total
Best Value
7 Set
$154$71$56.80
Save $97.20 total
Single
$22
Model 001
Foundation Brief - 3 Set
★★★★★4.8 · 200+ reviews·10,000+ pairs sold
$34.00$27.2020% bundle savings($9.07/pair)
Color
Noir
Size
Runs small, size up
·
Qty
1
$6.80 off applied
discount applied at checkout
Buy Now — $27.20
Free Shipping
Ships same day
30-Day Guarantee
Love it or we fix it
10°F
Cooler than cotton

Runs cool. All day.

Modal wicks sweat 50% faster than cotton. No swamp, no smell, no overheating.

Hotel sheets. Down there.

TENCEL™ Modal is the same fabric used in the world’s most expensive hotel sheets. Now against your skin all day. Certified clean, no synthetic chemicals. You’ll genuinely forget you’re wearing anything.

No rub. No raw.

Smooth fibers eliminate friction at the source. Dry skin doesn’t chafe, and Modal keeps it dry. Long run or long day, it just stops being a problem.

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30-day guarantee · Free returns

Pinned reviews
★★★★★4.9 · 200+ reviews
★★★★★
Doctor told me to ditch synthetics
Wife and I been trying to have a kid. Doctor flagged synthetic fabrics mess with sperm quality. Switched to Andros and it's been one of the easiest changes I've made. No polyester, no chemicals. Size up btw.
J
Jaylen P.
✓ Verified purchase
2 weeks ago
★★★★★
Lifting AM, running PM. These keep up.
Train twice a day and Andros is the only pair that stays dry through both. Thought the moisture wicking was marketing. Was genuinely shocked. Even squatting heavy they don't move. Game changer.
C
Colby A.
✓ Verified purchase
2 weeks ago
★★★★★
Only brand my husband asks me to reorder
Found these after reading about heat and male fertility. He loves them, says they feel athletic but without the PFAs. My son wants a pair just like dad. Plz make some for boys!!
S
Sarah M.
✓ Verified purchase
1 week ago
★★★★★
No more overheating. Should've done this sooner.
Play rec soccer and needed to run cooler. Temp difference is noticeable from the first wear. Comfortable the whole game, no bunching. These are my forever underwear.
J
Jay T.
✓ Verified purchase
today
★★★★★
Did my research. Andros won.
Two weeks comparing brands after learning about synthetics and test levels. OEKO-TEX, TENCEL Modal, no toxic dyes. Stuff they don't have to do but do anyway. Ordered 7 pairs. Worth every cent.
N
Nick S.
✓ Verified purchase
1 month ago
★★★★★
Just wanted good underwear. Got that.
Not a big health guy, just wanted something that fits and stays put. Soft, no shifting, no complaints. Runs small so size up. Got 3 in slate, ordering 3 more in black.
D
Dillon W.
✓ Verified purchase
4 weeks ago
FAQ
Frequently asked questions
Everything you need to know about the Foundation Brief.
Why not 100% cotton?
Cotton absorbs moisture and holds onto it, leaving you wet and uncomfortable. TENCEL™ Modal beech tree fibers are naturally moisture-wicking and temperature-regulating, keeping you dry, cool, and comfortable all day.
How does the Foundation Brief fit?
The Foundation Brief is designed with a modern, premium fit. Supportive coverage with a comfortable waistband that stays in place without digging in. We recommend ordering your usual size.
What makes TENCEL™ Modal different?
TENCEL™ Modal is derived from sustainably harvested beech trees. The fibers are softer than cotton, naturally breathable, and regulate temperature in real time. Cooler when it's hot, warmer when it's cold.
How should I care for the Foundation Brief?
Machine wash cold with like colors. Tumble dry low or hang to dry. Do not bleach or iron. These care instructions will help maintain the softness and performance of the fiber over time.