Frequently Asked Questions
Everything you need to know about Happy Banana merino wool boxer briefs.
Product
What are Happy Banana boxer briefs made of?
100% merino wool in the fabric. No polyester, no nylon, no spandex blended into it. The waistband is a standard elastic waistband, the same kind every boxer brief uses, so we call the fabric plastic-free, not the whole garment. No tag: care instructions are printed on the fabric.
Isn't wool itchy?
No. Merino fibers are much finer than traditional wool (17.5 microns vs 30 or more). They bend against the skin rather than poke. Most customers say our boxer briefs feel softer than cotton. If you have only met scratchy wool sweaters, merino is a different material.
Will they smell?
No. Merino manages moisture and its fiber surface slows the bacteria that make the smell. It does not kill bacteria; it never lets the party start. Most customers wear a pair 2 to 3 days between washes.
How do they compare to cotton underwear?
Cotton absorbs moisture and stays wet. Merino absorbs up to 35% of its weight while still feeling dry. Merino regulates temperature; cotton does not. Merino resists odor; cotton does not. Cotton wins on price. That is the honest comparison.
What's the inseam length?
4.2 inches. Long enough to prevent ride-up, short enough for comfort under any pants. We tested dozens of lengths before landing on 4.2" as the sweet spot.
Is it good for sensitive skin?
17.5 micron merino is soft and breathable, and there is no tag to rub. We do not make medical claims about skin conditions. If wool has bothered you before, try a single pair first. The 30-day guarantee covers it.
Does polyester underwear lower testosterone?
No human study shows that. The famous 1992 study used a polyester scrotal sling, not underwear, and serum hormones including testosterone did not change (Shafik, Contraception, 1992). Polyester textiles can carry endocrine-disrupting additives such as BPA, and PET, the plastic polyester is made from, has been found in men's semen. We do not claim our underwear raises or protects testosterone. We remove the plastic. The research, explained.
Sizing
How do I know my size?
Sizing runs true to standard men's underwear sizes. Between sizes, go up.
- Small: waist 28 to 30 in (71 to 76 cm)
- Medium: waist 32 to 34 in (81 to 86 cm)
- Large: waist 36 to 38 in (91 to 97 cm)
- Extra Large: waist 40 to 42 in (102 to 107 cm)
Do they stretch or shrink over time?
Merino has natural elasticity and holds its shape. Follow the care instructions (cold wash, lay flat or tumble low) and the fit lasts. High heat in the dryer can shrink it. Avoid that.
Can I mix sizes in a multi-pack?
Currently, each pack ships in a single size. If you need different sizes, order separate packs. We're working on mixed-size packs for a future release.
Care
How do I wash them?
Machine wash cold on the gentle cycle with a mild detergent. No bleach, no fabric softener. Lay flat to dry or tumble dry low. Merino resists odor, so you do not need to wash after every wear.
Can I put them in the dryer?
Yes, but only on the lowest heat setting. High heat will cause shrinkage. We recommend laying flat to dry for maximum longevity. Air drying is better for the wool fibers and extends the life of the product.
How long do they last?
With proper care, years of regular wear. Merino fiber is durable and springs back rather than pilling. Cold wash and low heat are the whole secret.
Shipping
Is shipping free?
US orders of $150 or more ship free, which covers the 5-pack and the 7-pack. A single pair ships for $14.95 in the US. International shipping is $40 flat.
How long does shipping take?
US orders: 5 to 8 business days. International orders: 10 to 15 business days. Every order ships from New York City with tracking.
Do you ship internationally?
Yes. International shipping is $40 flat. Duties and taxes, where they apply, are the customer's responsibility.
Returns
What's your return policy?
30-day money-back guarantee. Not for you? Email us within 30 days of delivery for a full refund. No questions asked.
Can I exchange for a different size?
Yes. Email us within 30 days with your order number and the size you need. We send the right size free, and you keep the original pair. No return required.
The Science
What does the research actually show?
Shafik, Contraception, 1992 (PMID 1623716): 14 men wore a polyester scrotal sling for 12 months. All reached zero sperm count after about 140 days. It reversed after removal. Hormones did not change. A sling, not underwear.
Hu et al., Toxicological Sciences, 2024: microplastics found in all 23 human testes examined.
Guo et al., Toxics, 2025 (PMID 40711011): microplastics in 34 of 45 semen samples. PET, the plastic polyester is made from, was the most common polymer.
Minguez-Alarcon et al., Human Reproduction, 2018: 656 men; boxer wearers had 25% higher sperm concentration than men in tighter styles. Fit and heat, not fabric.
Zleczewski et al., Translational Andrology and Urology, 2026 (PMID 42293842): controlled human studies comparing underwear materials are lacking. No one has run the fabric study.
Every source is linked on the research page.
Is merino proven to be better for fertility?
No. No one has run that study, and we will not pretend otherwise. What is documented: merino regulates temperature, absorbs up to 35% of its weight in moisture while feeling dry, and resists odor. What is also documented: plastic is in every testicle tested and PET is in semen. We do not promise an outcome. We remove an exposure. The swap takes 30 seconds.
Is this just fear marketing?
We cite peer-reviewed studies by author, journal and year, and we link every one. We also say what each study does not show, including the ones that do not go our way. Read them and decide. Our job is to give you a better option.
Still have questions?
Email us at hello@myhappybanana.com or try a pair risk-free with our 30-day guarantee.