Hi everybody i purchased an aquagard in line filter last year and am very plaesed with it.It filters out allbacteria,viruses, protozoa and retro fits to any bladder based system.Also comes with a tap adaptor to use if your not sure of a countrys' water purity or just want to get rid of the taste of chlorineit only weighs 100 grammes plus alittle more for the attachments.It filters 1600 litres and has an automatic cut off when this is reached.I got mine from backpacking light.co.uk I used mine in puddles in india and got clear tasty water.