Lightweight bag for summer
I love Sierra Designs for sleeping bags. In fact, I own 3 of them for myself. I love the Arrow Rock for mid summer here in the PNW in Washington. For 2lbs this bag is so light weight that it feels like nothing but it still very warm. I personally haven't tested it out to much below 40F but I feel the temperature accuracy is spot on. For most sleeping bags I always add 10F to their rated temp for comfort. If the bag says 15F it is really a comfortable 25 and so on. I also like the pillow picket underneath the hood to help prop you up for sleeping or reading. The stretchy baffles make sleeping in it a dream. I also haven't noticed any down leakage which has been a problem in a REI bag I own.