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Exposure to sand, rain, or water from any other source will not only damage your stuff it will have a serious impact on your ability to operate effectively when you are away from support. If you can't keep your stuff dry then you are not going to be dry and in the condition you need to be to operate to the best of your ability.
You can use stuff sacs to protect your equipment and make sure that it remains in pristine condition ready for use whenever you need it. You can fill your dry bags with anything that you want to keep safe. They come in a wide range of sizes from extra small all the way up to large so whatever you want to protect you will be able to find a stuff sac or dry bag that will hold it.
The Exped stuff sacs are made from taffeta nylon coated with polyurethane that will stop water, sand, and almost anything else getting inside the sac and damaging your property. These dry bags have a roll down top and also feature a grab handle that makes getting hold of the bag easy when you need to access the contents quickly.