Aegismax M3 Down Sleeping Bag Review

Like the M2 only better!

Aegismax, the company who gave us the M2 ultralight down sleeping bag, has made huge strides in design and comfort of their new M3 bag. We liked the M2 so much we had to try out the M3 and we weren’t disappointed. I ended up sending back my Teton Leaf 0° bag and trading up to the  M3. While the Teton definitely kept me warm in freezing temps it was bulky for backpacking. With the M3 only being marginally more expensive but significantly lighter and more compact, it was a better choice.


At the time of writing this article, the M3 is selling for $106 for the standard and $116 for the lengthened on AliExpress, with free shipping to the US (and now on Amazon with prime shipping too!). A similar quality bag made by a more well-known brand name would easily go for upwards of $200 making this bag a steal.



  • Splicing: yes
  • Filling:  95 % Goose Down
  • Fabric: Nylon
  • Size: 190x78cm(75in x 31in)/210x82cm(83in x 34in)
  • Style: Hooded mummy
  • Comfortable Temperature Scale: -8℃/-5℃ (18/23℉)
  • Maximum compression package dimension:13x20cm (5x8in)
  • Outer Fabric:iFlEX 15D 6500 Ultralight Nylon
  • Inner Fabric:iFlEX 15D 6100 Ultralight Nylon
  • Filling Material: 95% White Goose Down 500/550(lengthened bag) grams
  • Filling Power: 800
  • weight: 960g/1040g (34oz/37oz)
  • Colors available: Peacock Blue
  • Technical: Boxed Baffles



The M3 will keep you warm to temps below freezing. Three improvements from the previous M2 model make this bag significantly warmer. First, there is 200 grams more down filling to lock in heat. Second, the M3 has boxed baffles for keeping the down in place. Meaning the top fabric is sewn to an inner piece of fabric, which is then sewn to the bottom fabric, forming a fabric box for holding the down. When seams are sewn straight through, the down is compacted down at every seam and this can give the feeling of cold rings around the bag. Box baffles eliminated this problem and keep the seams as toasty as everything else in the bag. Finally, the M3 is a true mummy bag with a hood that you can cinch tight around your face.


The M3 ultralight bag comes in two sizes, the large can accommodate someone up to 6’10” and at 34″ wide, someone with broad shoulders as well. Even the standard is large enough for most people six feet and under.

The nylon used in the M3 is different than the M2. For one the denier has changed from 20D to 15D. Denier is a measurement of the thickness of the thread. One denier is the thickness of one silk thread. So the individual threads on the M3 are thinner which is actually a good thing because 20D can actually make a bag a bit stuffy. While the individual threads are thinner the thread count has been upped significantly which makes the bag durable and breathable while still being soft and offering some water resistance.


Our favorite feature of the M3 is that the standard and lengthened bags splice together. For a couple that backpacks, being able to cuddle on a cold night is a huge bonus. The upgraded zippers on these bags are also a welcomed change. The M2’s zippers seemed to snag every few inches but the M3’s glide effortlessly up and down. Middle of the night nature calls have never been so easy. The cinching down hood is also wonderful for keeping your head toasty on a freezing night.


There’s really only one con that we have found with the product itself and that is the size of the stuff sack for the standard length. Basically, the stuff sack is just too small. The lengthened bag has a bigger stuff sack and packing it away is as simple as with any compression sack. The standard bag’s compression sack is so small that stuffing the bag in is a comic exercise in futility. Stuff one section in and the other side pops back out. I am by no means a weakling, I lift weights regularly and am much stronger than I look, but I just did not have the strength to compress the bag back into the stuff sack. Even Patrick had a tough time getting it back in and only after much struggling was he successful.

To make packing in the woods practical you will either have to buy the lengthened bag with it’s bigger stuff sack or buy a bigger aftermarket stuff sack. With an only $10 difference in price from the standard to the lengthened that is probably the cheaper option. However, if you do go with the lengthened you will be adding a few ounces and inches to your pack weight and size.

The only other negative is the wait. You do need to order far in advance. These bags aren’t sold at REI, or on Amazon but on AliExpress and shipping from China can take close to 30 days. Update: These are now available on Amazon with prime shipping and Amazon’s great purchase protection.


If you are trying to decide between a better known brand and the Aegismax M3, save your money and get the M3. Aegismax has really worked hard to make this bag a great competitor with the big brands and I feel they have succeeded. From the quality fill, hassle free zippers, to the luxurious fabric, this bag can stand proud next to all it’s higher priced competitors.

If you are trying to decide between the M2 and M3, the M3 is the better bag with a few caveats. The M3 does weigh more and does not pack down as small as the M2. So if weight and pack size are top on your list of priorities you may want to go with the cheaper M2. You will sacrifice on temperature ratings though and you will have to deal with the inconvenience of a zipper that snags.

A last word of advice, with any down bag treating it with a down proofing product will increase both the warmth and the water resistance of the bag. So before you take you great new down bag on that next backpacking trip, follow our directions for caring for and treating your bag.