First off I have to say that I absolutely love the concept of these park series bags from Big Agnes, and I think with a little work they would have a winner. They are extremely roomy, which is paramount for me as I just can't get comfy in a mummy bag, and the Summit Park is light enough to pack. But the 15 degree rating on this thing is WAY over rated.

I have now spent several nights in cold weather in this bag down to the mid 20's. Have tried multiple pads with this bag. Two inflatables and a prolite 4. The last 2 nights with an Exped Synmat 9 Deluxe rated at R-6 and approx 0 degrees. With it, a full fleece liner and a layer of Capilene 4 I was just barely comfortable on cold ground surrounded by snow with temps about 25.

The down in the bag seems to work it's way towards the edges more than it should. BA says that they have corrected this with a different baffle design but I have the new design and it hasn't. There needs to be more down over the top of the body and not around the sides. Seems that in a race to produce the lightest that they gave up on comfort. I would gladly pack another 8 oz of down that stayed in place in this thing in exchange for comfort.

Oh, and the zipper ALWAYS gets hung up.

I have spoken with BA and they are great to work with, but even they suggested a liner or heavier insulated pad. Which I already have. They also gave me the name of a company that can do alterations and add more down. What would you bet they have had this complaint before.

These companies really should be held accountable for putting out these ratings hence the 2 stars. This is a 35 degree or better bag and if it would have been advertised as such, with a good zipper, it would be 5 stars. I am using this with equipment that is designed for colder weather. We should not have to go to extremes to make their rating work. There is only one other warmer pad that I am aware of and that is the Exped 9 Deluxe Downmat with an R-8 rating. I may get one, or I may just not camp in 25 degree weather any more.

Can some one please produce a true cold weather bag 0 degrees or so that is roomy, packable and comfortable?

Warm weather it's great. But I just spent one night in the upper 30's on this thing. It is NOT for the 35 degree weather that it is rated for. Even with a layer of Capilene 3, pants, tee, heavy fleece, and a BA Summit Park 15 degree bag I froze. Would not use it again below 50 degrees or so at least with any Big Agnes bag without a closed cell pad. And then you might as well of had an insulated pad instead. Comfort, small roll up size, weight and durability get a 4.5 out of 5 though.

I purchased an Exped SynMat 9 Deluxe for the BA Summit Park and it rocks in colder weather. A little heavy, but a bigger comfy bag and pad are the two luxuries I refuse to compromise on.

Fantastic product. Does exactly what it's supposed to do. Quick boil, light weight, super small, wide adjustable flame, sturdy wide support. One of the better products in my pack.