This bag is far and away the widest we tested and feels gigantic even when tightened with the adjustment straps.
The Kammok Thylacine down base bag on its own gets three ratings by the manufacturer: 29 ℉ Comfort, 18 ℉ Lower Limit, and -14 ℉ Extreme. Ignoring the "Extreme" rating, this bag lands squarely in the mid-twenties range and is a fairly accurate rating in our experience. The mummy bag shape is less drafty than some quilts of a similar rating, and so sleeps fairly warm. Kammok also uses a proprietary Insotect Flow design to keep the down from shifting to avoid cold spots, though they use a 750 fill power down, which isn't as high quality as some of the other bags. The CustomFit adjustments, straps that tighten the bag around you does help minimize dead air within the bag, also making the bag a bit warmer.
This category is where the Kammok bag is the weakest, weighing in at a whopping 35.8 oz. Most ultralight folks require a sleeping bag under two pounds, and the Thylacine is decidedly above that threshold. The numerous features, such as the two pockets and the CustomFit adjustments, as well as the 750 fill power down, prevent the Thylacine from being an ultralight bag. Overall, it scores the poorest warmth-to-weight ratio of the tested bunch.
The Thylacine is the heaviest bag we tested and has the largest stuffed size of any bag.
Even compared to other mummy bags, the Thylacine is heavier, larger, and packs down less. The shoulder and hip girth are five to ten inches larger than nearly other bag or quilt in the review, which may make the Thylacine a better choice for larger folks, but works against the goal of a fast and light sleep system.
As far as comfort goes, the Kammok Thylacine is quite comfortable and scores well on our scale. The Pertex Quantum fabric is nice to the touch, but the features mostly work against the comfort of the bag. The Thylacine is built as an extra wide bag and felt cavernous on our 5'8" and 5'5" testers. To eliminate the extra room it has four CustomFit adjustment straps, but even fully tightened, the bag still felt quite large. The internal zipper to attach the liner is also annoying and rubs if sleeping in just base layers.
The one feature that does bump up the comfort rating is the pillow pocket. While it does add a bit of weight, having a pillow that isn't a lumpy stuff sack that slides away in the middle of the night is quite nice.
Although we didn't test the entire Kammok Thylacine system, as a standalone bag, it doesn't seem overly versatile. The full-length zipper does allow for quite a bit of venting on a hot night, but the weight would make us hesitate to take this on a warm-weather trip, where something like the Feathered Friends Flicker or Enlightened Equipment Revelation would allow more adjustment and a smaller pack.
The Thylacine has elastic adjustment straps to minimize dead airspace inside the bag.
With the mummy and additional liner, Kammok lists the bag as going down to 16℉ but would cost an additional $199 with the liner. This seems somewhat gimmicky, as you could pair another liner with any bag to achieve similar results, and for probably less money. Similarly, adding insulated clothing to your sleep system would also keep you warmer, would be wearable around camp, and be more versatile on a trip, in keeping with the ultralight mindset.
What the Kammok lacks in attention to weight it makes up for in features. It comes with a whole host of them, some more functional than others. The feature we liked the most was the pillow pocket, where extra clothing could be stuffed to provide head support that stayed with you through the night. The CustomFit adjustment straps seemed a bit unnecessary to us, as they are there to compensate for the extra wide (70 inches!) build. We think that they could have been eliminated and have the bag be slightly narrower, and still be roomier than every other bag we tested. The other feature was a small stash pocket which felt a bit superfluous, as most ultralight folks would be sleeping with layers than also have pockets.
The Thylacine has a pillow pocket, which we really like, and the internal zipper for the mummy liner, which we found annoying.
We didn't test the Mummy Liner, but it seems to be far more expensive than other sleeping bag liners on the market and is heavier and twice as expensive than similar cold weather sleeping bag liners such as the Sea to Summit Thermolite Reactor Fleece Liner.
The Kammok Thylacine is a modular, heavily featured mummy bag that would work well for shoulder season camping, but perhaps not as good for ultralight hiking or other fast and light trips. The features keep it comfortable and warm, and the additional liner would likely allow you to push the use into cooler temps than other bags in the review. This bag is best suited for three-season car camping or short backpacking trips.
This bag retails just a hair under the average for this category. However, if you are looking for an ultralight sleep system you could either save money and go with an Enlightened Equipment Revelation 20 or upgrade to a lighter mummy bag like the Mountain Hardware Ghost Whisperer 20 or Marmot Phase 30.
The Kammok Thylacine is a comfy, warm mummy bag full of features. However, in exchange for those benefits are countered by the highest weight in the entire review. While the bag is comfortable, we think there are better choices for ultralight sleeping bags.