Using a Hunka bivy bag as part of your sleeping system will protect it from rain, drips and snow. What the Hunka is not is a permanent waterproof cover for your bag. Even though it is breathable you are likely to get a build up of moisture inside the bag which over period of time will make you bag feel clammy and eventually go mouldy. At every oppurtunity you should let your bag air.
Living with your Alpkit goodies and looking after them.
Some frequently asked questions and help topics to keep your Alpkit goodies in tip top order.