Rectangle-shaped sleeping bags go as much back as the late 1800's when a mail order catalog pioneer Pryce Pryce-Jones came up with the suggestion to attach 2 rectangular carpets together with ties. He is taken into consideration to be the innovator of today's contemporary rectangular sleeping bag design. After the war he had several of these bags still left as well as made a decision to market them to the public.
The shape of the real resting bag is to personal preference. The general selections are the normal rectangular form, the conical form, or the mommy bag. Some individuals might not such as the feel of sleeping in a regular rectangular shaped bag, favoring the closeness of a tapered one, whereas others may really feel too claustrophobic.
The last greatest factor to consider in selecting a bag is the insulation that is used in that bag. While both will do the work to maintain you warm, they both have their pros as well as cons. Some kind of extra padding under the bag is very advised.