Big Agnes Zirkel UL 20 and Q-Core SL

Editor: Cory McLaughlin

Just the Facts:

regular/up to 5’10” long/up to 6’6″
Pad Size Any 20″ wide Any 20″ wide
Color Sunflower/Graphite Sunflower/Graphite
Fill Type 850 fill DownTek™ 850 fill DownTek™
Fill Weight 15oz 15.5oz
Bag Weight 2lb 5oz 2lb 7oz
Shoulder Girth 67.5″ 72.5″
Hip Girth 64″ 69″
Foot Girth 43″ 44″
Stuff Sack Size S-7.5″x15″ S-7.5×15″

Bag Size 7″x6″ 7″x6.5″

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Size Color Rated To Weight Price
20″ x 66″ x 3.5″ Orange 15° 16oz $139.95
20″ x 72″ x 3.5″ Orange 15° 17oz $159.95
20″ x 78″ x 3.5″ Orange 15° 19oz $169.95
25″ x 78″ x 3.5″ Orange 15° 23oz $219.95
20″ x 72″ x 3.5″ mummy Orange 15° 16oz $159.95
20″ x 78″ x 3.5″ mummy Orange 15° 17oz $169.95

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My Story:
Nothing in life is as refreshing to the body as a night’s sleep. Sleep refreshes both the body and mind and without it you will certainly lose your edge. For a backcountry enthusiast sleep can be a bit of a challenge as weather and terrain can often work against the comfort that is necessary to sleep soundly. So, what are we to do? Often times the weather calls for sunny days but decides to change its mind halfway through the trip, or the temperature decides to drop far lower than predicted. So we try to plan for everything before we hit the trail. There are so many choices out there for pads and bags that one could easily find a bag for any weather. The key is to find one that is the perfect balance of warmth and weight. When going into the backcountry weight is of the utmost importance. Thanks to today’s technology and modern materials there are a number of light weight options that can provide 3 season comfort. Thankfully Big Agnes (BA) has set themselves apart as one of the leading brands of light weight high quality sleeping bags and pads and other products.
While planning an Idaho elk hunt I was searching for new products to review. I was in need of a sleeping bag and pad. As luck would have it I had already been in contact with a BA and was working out the details of a Zirkel UL 20 sleep system. I was sent the Zirkel UL 20 and the Q-Core SL insulated sleeping pad just in time. The products arrived and I was instantly impressed with them. The sleeping bag comes with two bags, one large bag to allow for storage without compression, and one small compression bag for use while hiking. The pad has its own small bag for storage and fits perfectly unlike many others that never seem to fit right after you unfold them. My pack was filled and I was ready to get into the woods.
I was soon locking my truck and heading out into the field. My camp was near a small stock pond that sits about 2 miles away from the road. It was early September and the temperature was in the mid 80’s during the day and into the low 40’s at night. I knew I was not going to be able to test the lower limits of the bag but you have to play the cards you’re dealt right?

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The Zirkel UL 20 is a bag unlike any other I have used. The people at Big Agnes really put some time into development of this bag. The first thing I noticed was the weight. The Zirkel comes in at only 2lbs 5 oz. The second thing was the material itself. The Zirkel has 850 weight fill of DOWNTEK water repellent down insulation. This is a great feature as down can be susceptible to moisture accumulation. This also helps to preserve loft which is what provides the insulation. The bag material is Pertex rip-stop nylon. It is silky smooth and water repellent. The real innovative feature that caught my eye was the pad pocket on the bottom of the bag. There is a built in pocket and retaining strap for the sleeping pad that keeps the bag on the pad.

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The pad pocket is two part as the Zirkel does not have fill on the bottom half of the bag. This is done to save weight but also as a design element. As I said above loft provides insulation. When your body weight is compressing the fill you lose loft and thus you lose insulation. This is where the pad pocket comes in. The BA Q-Core SL is a 3.5’’ insulated pad that creates the sleeping base while also providing comfort and insulation. The two work together as a unique and innovative system.

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The Q-Core SL pad is thick! It is the thickest pad I have ever used. Do not be fooled into thinking that all that comfort comes at a cost as the pad still comes in at only 17 ounces. For a pad that offers an R value of 4.5 that is pretty dang light. I found this pad to be incredibly comfortable and warm. I will say that it takes some serious lung power to get it filled up. I averaged just over 30 breaths to inflate the pad. This was not really a concern to me as I was just sitting at camp anyway. This pad was great and preformed exactly as advertised. I have seen reviews from others that believe this pad to be too narrow and slightly shorter than advertised. I personally had no issue with the pad and found it to offer exceptional comfort and a great nights sleep.

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The entire sleep system weighs just 3lbs. 6 oz. It fits nicely into any back pack and is rated to 20 degrees F. This system is fantastic! It is comfortable and warm. I am 5’ 9’’ and 180 pounds and the regular sized bag felt roomy and was extremely comfortable. I love the zipper on this bag as well. BA added a very tough fabric around the teeth that helps to prevent any of the bag getting caught in the zipper and that is a huge improvement to many of the other bags from other companies. The internal pillow pouch was useful to hold my folded up coat and give me a nice place to rest my head. I also like the collar as it really helps to seal in the heat.
At the end of my trip I was exhausted but it was not for lack of sleep. My nights were warm and comfortable. Unfortunately, I was not successful in my hunt, but I was successful in finding a great new piece of gear that I feel confident will continue to provide great comfort on future trips. If you are looking for a lightweight sleeping system you should seriously consider looking into Big Agnes and the Zirkel UL 20 with the Q-Core SL sleeping pad. I am sure you will not be sorry that you did.

What could be done better?
I cannot find anything that I would do better with this system. If used in accordance to the manufactures recommendations I do not feel that any serious improvements could be made. I would like to see the pad extend all the way out to the end of the bag as I had to use my pack to support my head. In fairness I was not able to test the bags lower temperature limits so I cannot comment on the 20 degree rating. I will say that I while it takes a tremendous amount of lung power to fill the sleeping pad I see no way to improve that. The provided comfort is worth the effort. You will absolutely love this system, and I recommend it without reserve.
If future trips afford the opportunity for sleeping in colder conditions I will update this review if there are any changes to my feelings about this system. I give this 4.75 stars as is and would gladly bump it up to 5 if it continues to perform at or near the lower limits.

  • Functionality
  • Value
  • Ergonomics
  • Durability