A sleeping bag is an insulated covering for a person, essentially a lightweight quilt that can be closed with a zipper or similar means to form a tube, which functions as lightweight, portable bedding in situations where a person is sleeping outdoors. It is also commonly used indoors for people who do not have beds or at sleepovers. Its primary purpose is to provide warmth and thermal insulation through its synthetic or down insulation. It also typically has a water-resistant or water-repellent cover that protects, to some extent, against wind chill and light precipitation, but a tent is usually used in addition to a sleeping bag, as it performs those functions better. The bottom surface also provides some cushioning, but a sleeping pad or camp cot is usually used in addition to that purpose. The bottom surface of a sleeping bag may be moderately water repellent, but a plastic tarp or groundsheet is often used to protect against moist ground.
A mummy bag, so named because it has an insulated hood which keeps the head warm. A foam sleeping pad can be seen underneath the sleeping bag.
A three-person buffalo sleeping bag used during Arctic exploration circa 1880
Russian sleeping bag used in space station Mir and International Space Station
A highly compact sleeping bag measuring 23 cm (9 in) with a diameter of 12 cm (5 in) when packed but 210 cm × 65 cm (6.89 ft × 2.13 ft) when unfolded.
A zipper, zip, fly, or zip fastener, formerly known as a clasp locker, is a commonly used device for binding together two edges of fabric or other flexible material. Used in clothing, luggage and other bags, camping gear, and many other items, zippers come in a wide range of sizes, shapes, and colors. In 1892, Whitcomb L. Judson, an American inventor from Chicago, patented the original design from which the modern device evolved.
Zippers with common teeth variations: metal teeth (top), coil teeth and plastic teeth
Examples of special zippers with different tape materials, colors and patterns.
A two-way (double-separating) zipper.
A coil zipper with its slider removed.