Fast SteriPEN® water purifiers are fast. They are proven to eliminate viruses, bacteria and protozoa in 0.5 liters (16 oz) in 48 seconds. Compare this to chemicals like chlorine that take up to 4 hours to do this job or iodine, which can’t eliminate some protozoa at all! SteriPEN’s speed means you can drink quickly. Light SteriPEN® water purifiers are light. The SteriPEN Classic weighs less than 225 g (8 ounces) with batteries and the Adventurer/Traveler family weighs less than 110 g (4 ounces)