Men's Classic Thermal Merino Base Layer Crew Boxed

Pure 100% Merino Warmth. Gold-Standard Cold Weather Layering.

The Smartwool Men’s Classic Thermal Merino Base Layer Crew (formerly the Merino 250 Crew) is the gold standard for cold-weather mountain insulation. Built entirely from 100% responsibly sourced Merino wool, this heavy-midweight top breathes exceptional warmth into your layering system while naturally regulating body temperature and suppressing odors through multi-day trips.

• 100% Merino Wool Construction: Premium 250g interlocking knit fabric delivers deep thermal insulation, active moisture management, and natural odor resistance.

• Updated Fit & Shoulder Seam Construction: Shoulder panels eliminate top-of-shoulder seams to prevent chafing under heavy backpack straps and hydration packs.

• Chafe-Free Flatlock Seam Construction: Smooth, flatlock seams lie flat against your skin to minimize friction during aggressive skiing, touring, or hiking.

• Side Seams Wrap to Front: Ergonomic side seams sweep toward the front for a superior body-contouring fit that moves naturally with your torso.

• Crew Neckline & Back Body Drop: Classic crew neck design layers cleanly under fleeces and shell jackets, while a drop-tail hem keeps your lower back covered when bending or reaching.

• Slim/Active Fit: Tailored silhouette hugs the body to maximize thermal efficiency and moisture transfer without feeling restrictive.

Why the Attridge Staff Chooses Merino

"Our staff almost exclusively choose Merino wool for their base layer. Its secret weapon isn't just how warm it keeps you on sub-zero mornings—it's Merino's incredible ability to self-regulate and dump excess heat the moment you start charging hard, hiking the ridge, or lapping the park. You stay in that perfect thermal sweet spot all day without overheating or getting that cold, clammy synthetic chill on the chairlift ride back up. Once you ride in pure Merino, you'll never go back."