Men's Kobuk Heavyweight 100% Merino Wool 1/4 Zip
Named for Alaska's Kobuk Valley—where caribou migrate by the hundreds of thousands and winter temperatures plunge to fifty below—this quarter zip is built for those who refuse to come inside. At 400 GSM, this is true heavyweight merino, not the "heavyweight" label some brands slap on 250-300 GSM midweight fabric. When you're the first one out and the last one in, when wind and snow can't convince you to quit, this is the layer that keeps you going. Thumbholes lock your sleeves in place under gloves, the YKK zipper vents heat on demand, and the zipper garage keeps cold metal off your chin.
Why You'll Love This 1/4 Zip
Most "heavyweight" base layers on the market weigh in around 250-310 GSM. At 400 GSM and 544 grams in size large, this is genuine expedition-weight merino—the kind trusted by ice fishermen, ski patrol, and anyone whose work or play demands hours in brutal cold. The 18.5 micron Australian merino stays soft against your skin despite its substantial weight, while flatlock seams prevent chafing during all-day wear. The mock neck blocks wind from sneaking down your collar, and the YKK semi-auto locking zipper stays exactly where you set it.
Why 100% Merino?
Some brands reinforce their merino with synthetic blends. This quarter zip is 100% Australian merino wool—no polyester fillers, no nylon additions. That means superior temperature regulation whether you're working hard on the ascent or standing still on the ice. Merino wicks moisture, resists odor naturally, and keeps insulating even when wet. When you're hours from shelter in unpredictable weather, that's the difference that matters.
Size & Fit
Regular fit with room to breathe—true to size with space for a lightweight base layer underneath. Size down if you prefer a more athletic fit.
| Size | Chest (in) | Waist (in) | Sleeve (in) |
|---|---|---|---|
| XS | 33-35 | 24-27 | 30-31 |
| S | 35-38 | 28-30 | 31-32 |
| M | 39-41 | 31-33 | 32-33 |
| L | 42-45 | 34-36 | 33-34 |
| XL | 46-48 | 37-40 | 34-35 |
| 2XL | 49-52 | 41-44 | 35-36 |
| 3XL | 52-54 | 45-49 | 36-37 |
Care Instructions
Machine wash cold on gentle cycle, tumble dry low. Use Nikwax Wool Wash or mild detergent—never fabric softener or bleach. Turn inside out before washing. Store in airtight container during off-season to protect from moths.
Complete Your Look
Pair with the Katmai Heavyweight Pants for complete Arctic coverage, or layer over a midweight crew when temperatures go truly extreme. Browse the full Minus 33 collection for more expedition-weight essentials.
Men's Kobuk Heavyweight 100% Merino Wool 1/4 Zip
Named for Alaska's Kobuk Valley—where caribou migrate by the hundreds of thousands and winter temperatures plunge to fifty below—this quarter zip is built for those who refuse to come inside. At 400 GSM, this is true heavyweight merino, not the "heavyweight" label some brands slap on 250-300 GSM midweight fabric. When you're the first one out and the last one in, when wind and snow can't convince you to quit, this is the layer that keeps you going. Thumbholes lock your sleeves in place under gloves, the YKK zipper vents heat on demand, and the zipper garage keeps cold metal off your chin.
Why You'll Love This 1/4 Zip
Most "heavyweight" base layers on the market weigh in around 250-310 GSM. At 400 GSM and 544 grams in size large, this is genuine expedition-weight merino—the kind trusted by ice fishermen, ski patrol, and anyone whose work or play demands hours in brutal cold. The 18.5 micron Australian merino stays soft against your skin despite its substantial weight, while flatlock seams prevent chafing during all-day wear. The mock neck blocks wind from sneaking down your collar, and the YKK semi-auto locking zipper stays exactly where you set it.
Why 100% Merino?
Some brands reinforce their merino with synthetic blends. This quarter zip is 100% Australian merino wool—no polyester fillers, no nylon additions. That means superior temperature regulation whether you're working hard on the ascent or standing still on the ice. Merino wicks moisture, resists odor naturally, and keeps insulating even when wet. When you're hours from shelter in unpredictable weather, that's the difference that matters.
Size & Fit
Regular fit with room to breathe—true to size with space for a lightweight base layer underneath. Size down if you prefer a more athletic fit.
| Size | Chest (in) | Waist (in) | Sleeve (in) |
|---|---|---|---|
| XS | 33-35 | 24-27 | 30-31 |
| S | 35-38 | 28-30 | 31-32 |
| M | 39-41 | 31-33 | 32-33 |
| L | 42-45 | 34-36 | 33-34 |
| XL | 46-48 | 37-40 | 34-35 |
| 2XL | 49-52 | 41-44 | 35-36 |
| 3XL | 52-54 | 45-49 | 36-37 |
Care Instructions
Machine wash cold on gentle cycle, tumble dry low. Use Nikwax Wool Wash or mild detergent—never fabric softener or bleach. Turn inside out before washing. Store in airtight container during off-season to protect from moths.
Complete Your Look
Pair with the Katmai Heavyweight Pants for complete Arctic coverage, or layer over a midweight crew when temperatures go truly extreme. Browse the full Minus 33 collection for more expedition-weight essentials.