The robust bottle holds 0.65 litre of filtered water and is equipped with a fold-up bite valve and snap hook. The two-stage filter cleans up to 4000 litres of contaminated water and contains no chemicals, batteries, or moving parts like many other water filters on the market. The two-stage filtration process removes bacteria and protozoa and reduces organic chemicals and chlorine. The hollow fibre membrane filter should be replaced after approximately 4000 litres. It is also ideal for city trips. The replaceable activated carbon capsules remove bad taste, chlorine, and organic chemicals. These capsules are individually replaceable and should be replaced after 100 litres or three months after first use.