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SITKA Gear | 10.15.2018

Understanding Kelvin Insulation | SITKA Gear

  • Pursuit: Big Game
  • Environment: Subalpine, Open Country

When it comes to insulation, we’ve designed varying configurations to accommodate niche weather conditions and activity levels for big game hunting. Fit, face fabric, insulation type and fill are all tailored to a certain application. Below we’ll breakdown these variables and explain each Big Game model.

SITKA Gear Open Country insulated jacket.


Primaloft Gold Down Blend: A hybrid insulation yielding the benefits of goose down and synthetic down. Synthetic fibers acts as scaffolding for the goose down to retain its structural integrity, increasing loft and reducing drying time while making the insulation less likely to clump. A hydrophobic treatment increases moisture resistance.

Primaloft Hi-Loft: A fully synthetic insulation designed for durability. While it doesn't compress as much as down insulation, it will dry incredibly fast and retain most of its loft/heat retention ability no matter how many times it has been compressed.

Polartec Alpha: The most breathable insulation in our Big Game line. It is a fully synthetic, non-migrating insulation, which allows us to use a softer, quieter and more breathable face fabric that increases convective cooling since it is more air permeable. This insulation will wick itself dry very quickly and is designed for the wearer to hike hard and sweat it out.


Performance: A streamlined fit that is low-bulk and designed for minimal layering.

Standard: Designed to accommodate mild layering for more versatility from early to late season climates. 

Expedition: This is our roomiest fitting gear to go over all other layers easily. It allows for maximum layering in harsh conditions.


High: Insulation designed and constructed for maximum breathability to purge moisture while providing thermoregulation during high output activity.

Medium: Balances breathability with the right amount of insulation for medium, stop-and-go output in cold conditions or high output in extremely cold conditions.

Low: Provides the highest thermal value for static activity in cold and extremely cold conditions.

Kelvin Active Jacket

A true hybrid designed to stay on your back whether you’re crushing uphill or waiting out a cautious bull. Highly breathable, lightweight, quick drying, packable, and quiet, the Kelvin Active is best for warmer conditions or on-the-go hunters.

  • Activity Level: High
  • Fit: Performance
  • Weight: 13.7 ounces
  • Insulation: 80 g/m2 Polartec® Alpha® Insulation
  • Fabric: Shell: 20-Denier Nylon Ripstop // Liner: Breathable Polyester Mesh
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The Kelvin Active Jacket is one of the primary components to my archery elk hunting system. I typically wear it as an outer layer, usually over a Core Lightweight Crew base layer and an insulating vest like the Kelvin Lite. As the season progresses and the temperatures drop, I’ll use it in place of the Kelvin Lite Vest as an internal insulating piece, and top it off with an outer layer like the Traverse Cold-Weather Hoodie or the Jetstream Jacket, depending on the conditions. —Corey Jacobsen

A hunter bugles for elk.

Kelvin Lite Hoody

Worn as an outer layer or underneath a shell, the Kelvin Lite Hoody is built for lightweight, all-over warmth. The jacket is body-mapped with side panels to thermoregulate high-heat areas of the body. These side panels are made of a more breathable face fabric and Polartec Alpha Insulation to allow quicker dry time and convective cooling. The rest of the jacket is uses a quiet face fabric that is more wind resistant, providing a wider range of uses.

  • Activity Level: Medium
  • Fit: Standard
  • Weight: 16.9 ounces
  • Insulation: 80 g/m2 PrimaLoft® Hi-Loft with Polartec® Alpha® Active Insulation in Side Panels
  • Fabric: Shell: 27-Denier Polyester Woven Ripstop // Side Panels & Liner: 20-Denier Stretch Nylon Ripstop
shop now Glassing in Optifade Subalpine.

Kelvin Jacket

Built with our Expedition fit for maximum layering underneath, this is a step warmer than our Kelvin Lite Hoody. The hoodless design makes it easier to layer under a shell in wet weather.

  • Activity Level: Low
  • Fit: Expedition
  • Weight: 24.8 ounces
  • Insulation: 170 g/m2 PrimaLoft® Silver Insulation
  • Fabric: Woven Polyester Face
shop now Shed hunter finds much success.

Kelvin Down WS Hoody

When faced with extreme cold or windy conditions, reach for the Kelvin Down WS Hoody. Filled with Primaloft Gold Insulation Down Blend, this is a sleeping bag for your upper body that incorporates lofty, hydrophobic insulation. A box baffling method retains loft where baffles meet, improving thermal retention. The face fabric includes a GORE® WINDSTOPPER® membrane to block bone-chilling gusts and a roomy Expedition Fit allows for easy layering over all other gear. While heavier than our other insulation pieces, it is highly compressible and performs the tasks of two jackets: down insulation and a windproof softshell.

  • Activity Level: Low
  • Fit: Expedition
  • Weight: 27.3 ounces
  • Insulation: 250 Grams of PrimaLoft® Gold Down Blend Insulation // 70/30 Blend of 750-Fill Goose Down & Synthetic Fibers
  • Fabric: Water-Resistant GORE® WINDSTOPPER® Shell
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Quality time glassing is key on bighorn sheep hunts. When I get to a glassing location, my binos, tripod, spotting scope and Kelvin Down WS Hoody come out of my pack. The hoody goes on allowing me to spend more time behind the glass in terribly cold conditions. During the freezing cold and long winter nights, I lay the hoody at the bottom of my sleeping pad for extra insulation and warmth. This is my ‘survival’ piece, if I ever get sweated up or cold, the Kelvin Down Hoody goes on. —Cam Foss

Hunter glasses in the insulated Kelvin Down Hoody.