Merino Wool Boxer Briefs

100% merino wool in the fabric. Zero polyester, zero nylon, zero spandex where the boys live.

What are Happy Banana boxer briefs made of?

100% merino wool at 17.5 microns. That is about half the thickness of the wool in an old sweater, which is why these feel soft instead of scratchy. There is no polyester, nylon or spandex in the fabric. The waistband is a standard elastic waistband, the same kind every boxer brief uses, and we tell you that instead of pretending the whole garment is plastic-free. Fly front. No tag. Care instructions are printed on the fabric.

Why not polyester underwear?

Polyester is plastic. You wear it all day on the most absorbent skin you own.

Researchers found microplastics in all 23 human testicles they tested (Hu et al., Toxicological Sciences, 2024). A 2025 study found microplastics in 34 of 45 semen samples, and the most common plastic was PET, the polymer polyester is made from (Guo et al., Toxics, 2025). Testing by the Center for Environmental Health found BPA in polyester activewear at up to 40 times California's safe-harbor limit.

None of that proves polyester underwear hurts you. No one has run a controlled human study comparing underwear fabrics under normal wear, and a 2026 urology review says so plainly (Zleczewski et al., Translational Andrology and Urology, 2026). We read that and made a decision. You can wait for the study, or you can spend 30 seconds and remove the exposure. The full research, with every source linked.

Merino wool vs cotton underwear: what is the difference?

Cotton soaks up sweat and stays wet. Merino absorbs up to 35% of its weight in moisture and still feels dry, then lets it evaporate. Merino regulates temperature, cool in summer and warm in winter. Merino resists odor because it keeps the fabric dry and its fiber surface slows the bacteria that make the smell. Cotton wins on price. That is the whole comparison.

How do they fit?

Snug, not tight. 4.2 inch inseam, long enough that nothing rides up. Sizes S (28 to 30 in), M (32 to 34), L (36 to 38), XL (40 to 42). Between sizes, go up.

Which pack should I buy?

One pair at $34 if you want to meet the fabric first. The 5-pack at $150 is $30 a pair and ships free in the US. It covers a week without a mid-week wash. The 7-pack at $189 is $27 a pair, ships free, and clears the drawer in one order.

Shipping and returns

US orders of $150 or more ship free. A single pair ships for $14.95 in the US. Made in China, ships from New York City in 5 to 8 business days. Thirty-day money-back guarantee. Wrong size? We send the right one free and you keep the original.

How do I wash merino boxer briefs?

Machine wash cold, gentle cycle, mild detergent. No bleach, no fabric softener. Lay flat or tumble dry low. Merino resists odor, so it needs fewer washes than cotton or polyester.

Specs

• 100% merino wool fabric, 17.5 micron
• No polyester, nylon or spandex in the fabric
• Standard elastic waistband
• 4.2 inch inseam, no ride-up
• Fly front, tag-less
• Sizes S (28 to 30), M (32 to 34), L (36 to 38), XL (40 to 42). Between sizes, go up
• Made in China. Ships from New York City
• 30-day money-back guarantee, free size swap