Smartwool Merino Boxer Boxed Men's Thermal Underwear - Black, Size M

For the active man who demands comfort without compromise, the Smartwool Merino Boxer Boxed delivers all-day performance. Whether you're hiking rugged trails, traveling light, or simply navigating a busy workday, these boxer briefs keep you dry, fresh, and perfectly regulated. The slim fit and 6-inch inseam provide a modern silhouette that stays put without bunching, while the functional fly and flatlock seams ensure effortless wear from morning to night.

Key specifications

• Material: 87% Merino wool, 13% nylon with core-spun technology for enhanced durability
• Fabric weight: 150 g/m² – lightweight yet substantial for year-round comfort
• Fit: Slim fit with 6-inch inseam (approx. 15 cm) for a sleek, athletic profile
• Waistband: Elastic, Merino-lined for softness and secure hold
• Seams: Flatlock construction to prevent chafing during high-movement activities
• Fly: Functional fly for convenience
• Odor resistance: Natural Merino wool properties keep odors at bay
• Moisture management: Excellent wicking to keep you dry
• Temperature regulation: Adapts to body heat for comfort in varying conditions
• Breathability: Highly breathable fabric prevents overheating
• UPF rating: 20+ for added sun protection
• Care: Machine wash cold, gentle cycle; tumble dry low; do not bleach, iron, or dry clean

Why choose it

Merino wool is nature's performance fiber, and Smartwool has perfected its use in underwear. The boxer briefs resist odor naturally, so you can wear them multiple times between washes—ideal for travel or multi-day adventures. Core-spun technology wraps Merino around a nylon core, boosting durability without sacrificing softness. Flatlock seams eliminate irritation, and the Merino-lined waistband stays comfortable all day. Whether you're on the trail or at the office, these boxers provide the perfect balance of performance and everyday comfort.

Ideal use cases

• Hiking and backpacking in variable weather
• Travel and commuting with limited laundry access
• Everyday wear for work or leisure
• High-intensity activities where moisture management matters
• Year-round use as a base layer in cool or warm conditions

Good to know

Merino wool naturally regulates temperature, wicks moisture, and resists odor, making these boxers a versatile choice for any activity. The slim fit sits close to the body without restricting movement, and the 6-inch inseam prevents ride-up. Follow the care instructions to maintain the fabric's performance and longevity. With UPF 20+ protection, they offer an extra layer of defense during outdoor pursuits.