Semi-Rectangular: I call this the cross. This backpacking bag is rectangle-shaped ahead and afterwards slenders along towards the feet. With this type, you obtain added space, but not as much weight as a true rectangular resting bag. For those who are claustrophobic, like me; we can reach sleep a little better inside a bag with added room in it and still have some benefit from the form.
It is very important to bear in mind though that the temperature rankings are overviews for recommendation only. Because, much like spicy food, consuming a jalapeno pepper for some isn't really a big deal ... but for others eating one would certainly seem like it would melt the skin straight off their tongue. The exact same goes with a sleeping bag. A +20 level rating would indicate that for most the bag would certainly be cozy sufficient. The most effective way to pick a cozy enough bag is to go with one that handles a 10 degree chillier weather condition than what you're anticipating to be sleeping in. Selecting in that manner needs to have you ... covered. (No pun planned.) And once more of course, appropriate sleep wear should fit the chillier or warmer demands you may have.
Draft Tube/Draft Flap: This is a flap or tube that leaves side the zipper. This flap helps reduce warmth loss. When choosing a treking rest bag, validate that the flap is simply sewn on the cellular lining as well as not with the bag. Make certain you analyze the zipper prior to purchasing to verify that the flap/tube doesn't problem or get captured in the zipper course. Fill: There are two fundamental options of bag fills; Fabricated (polyester) and Down (shielding feathers of ducks or geese).