In another post months ago, there was a discussion about gravity filters. Jason Klass posted his DIY filter using a Katadine filter and a bag of his design. I was inspired by the fact of not having to pump water. I went looking around for that filter and couldn't find it for my impulse purchase. I ended up buying the Katadine Base camp. But found the bag bullit proof and on the heavy side. My plan now is to retro fit the filter into a Jason Klass type bag.