Rectangle-shaped: These are specifically like the term recommends. A big rectangular shape. As a result of their form, they tend to be the least functional style of sleeping bag. There is a bargain of room within the bag for the body to warm up. Because of their heavy weight, they might be far much better matched for a "Automobile Camping" journey instead of a backpacking tour. They do have the benefit of a set of bags being able to be zipped collectively as well as come to be a resting bag for a couple rather than one person. With this style, a full or queen blow-up mattress beneath truly contributes to a pleasurable evening's sleep. (Once more not advised for the back country).
In 1917 the zipper was developed and, of course, these made for a terrific seal for the rectangular sleeping bags allowing an individuals body warmth to remain trapped longer consequently keeping them warmer on those cold winter season evenings. Basically the term resting bag essentially suggests a safety bag for someone to rest in.
The other sacrifice is the size or thickness of the bag. A mummy sleeping bag essentially will certainly be much smaller sized for bring around which is why it is a preference for many backpackers/hikers. The rectangular resting bag isn't as small yet because it's not common to be lugging it, apart from somewhere in a vehicle while getting to your intended location, the bulkiness of the bag is not as large a problem.