When it comes to packing it, you usually have one of two choices:
1) A compression bag – squeezes it down small but leaves it at risk of getting wet
2) A dry bag – keeps those precious feathers dry but leaves you with a big, bulky stuff sack
Now you have the option 3)
The working principle of it is very simple:
Like any other compression bag (sometimes called spider compression sacks because of their dangling straps/legs), you stuff your sleeping bag, clothing or whatever into the sack and close it. You then pull the straps tight to squeeze the air out and – hey presto – your package is as small as it’s ever going to be.
Of course, if want your sleeping bag to stay dry then using a waterproof material with a watertight seal means the air can’t escape so the compression doesn’t work. However, those clever outdoor designers have added a tiny rubber valve to their compression dry bags which allow you to squeeze out all of the air whilst still keeping your sleeping kit dry.
(Cut out of Ortlieb drybag review from http://thenextchallenge.org)
Want to learn more about its full specifications?
Learn more >> Dry bag with valves by KakiOutdoor