If you see a +20 degree score that would certainly indicate that the bag should be cozy enough for temperatures that are 20 levels or warmer.. And if you see a - 20 level score then it has actually been figured out that the bag needs to be cozy sufficient for minus 20 degree climate.
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 significant difference between both styles is the cut and also form of the bags. The mummy bag is extra restricting. You can think about it like your own individual cocoon where you can go to bed in the evening as a caterpillar as well as wake up the next early morning as a butterfly. You're completed tight with not a lot of area to relocate. The rectangle-shaped bed on the other hand gets its name from its rectangle-shaped form as well as lets you relocate your legs.