The Army issues 3 sleeping bags (I'm sure someone will correct me if I'm wrong), an Arctic bag, a summer bag and the one you have, Its a synthetic hollow fill, not sure of the rating but I've been in one in -10 in Germany and it's been fine. The mesh pockets are for drying kit when you sleep. The bag is OK, quite well made but soldiers tend to replace it with a lighter/smaller one if they have to carry it around with them. Hope that helps mate,
Brian