Jacob McDonald wrote an answer about Osprey Packs Sirrus 36 Backpack - 2100-2300cu in - Women's on August 15, 2013
I have the stratos 36 (the male version of this pack) I have used this backpack for two years now as an ultralight pack for my gear. Have done 4 days out of it with a big agnes 20 degree bag. In the summer I have a BA 45 degree bag that is perfect for this pack. Unless you are an ultralight/minimalist, this bag will be to small. With a normal size sleeping bag in it, you only have enough space for a smaller cook-set and a little bit of food. When using this on extended trips, I have always had to strap my hydration bladder to the outside of the bag too. Great pack but you really have to leave luxuries home if you plan on using it for an extended trip.