This is a serious portable water filter from Katadyn. It’s efficient because it uses a ceramic filter, which will not let anything larger than 0.2 microns through. It also has a long life — it will filter up to 13,000 gallons before you need to replace the cartridge. The filter eliminates bacteria, viruses, cysts, protozoa, algae, spores, sediment and reduces radioactive particles.
Home page: Katadyn
Available from Amazon for $189.