Kammok Thylacine

Our take If you want three bags—one for summer, one for shoulder season, one for winter—but are on a two-bag budget, the Kammok Thylacine is the solution. The full system has three components, all filled with 750-fill down: 1) a standard mummy bag; 2) a liner; 3) a liner insert.

Comfort The bag has a whopping 70 inches of shoulder room—typical mummies are closer to 60 inches in circumference—resulting in high praise from our taller and broader testers. Aside from comfort, this allows the liner and insert to fully loft for cold weather. Downside: Average-size testers were chilled in just the mummy bag with temps in the mid-30s due to all the extra space. And there’s a weight penalty.

Custom fit Compression straps on the exterior top of the bag allow you to tailor the width around your chest, waist, knees, and ankles. Testers had mixed results—they liked shrinking the footbox size to make it easier to heat up, but doing so took a significant amount of fiddling to get the right balance between comfort and warmth. Most testers set it and left it.

Warmer The liner nests in the main bag via a 60-inch zipper along the right shoulder and hip, as well as eight interior 5-inch Velcro attachments. Adding the liner turns the 30°F mummy into a 15°F system. 

Warmest The liner insert (it attaches inside the first liner via a series of toggles) upgrades the bag to 0°F. “We used this system in everything from beautiful alpine summer nights to raging fall storms to cold ski-touring adventures, and whatever combination of liners and bags we had, we always slept warm,” said an Alaska tester after a full season of use.