Unless you are in the military, one of the top priorities when hiking and backpacking is keeping the essential kit light. A pack that feels light after five minutes in the comfort of your living room may appear to increase alarmingly in weight when you have been on your feet all day with it on your back. One of the ways in which to shave off a few critical grams or ounces is to make a careful selection when it comes to sleeping bags. The other consideration is the compressibility of your chosen bag. Generally speaking, when it comes to both weight and size benefits, down-filled models will win over synthetic options every time. Furthermore, the higher quality the down then the lighter and more compressible it will typically be. Top-end down, usually goose down, requires a lower quantity of product to fill and so achieve a higher temperature or comfort rating. However, top quality down usually comes with a higher price tag. The design will also play some part, both with regard to weight and size. Mummy style sleeping bags use less material than rectangular bags so it makes sense that they will be typically lighter and compress smaller.