SteriPEN is a hand held water purifier that uses ultraviolet light to purify up to 1 liter (32oz) of water at a time. There are no chemicals to taste or smell, no pumping or test strips, and no setup or clean up involved! The revolutionary SteriPEN Journey LCD uses universal symbols to take the guesswork out of the water purification process. Journey's integrated LCD screen displays the user's dose selection (1/2 liter or 1 liter), battery status and countdown timer. The LCD screen also tracks the number of uses and signals when lamp usage approaches its life limit. At 8,000 cycles, lamp life for SteriPEN Journey LCD reaches a new high (1 liter 4 times a day for nearly 7 years). Like all SteriPENs, the Journey is fast (48 seconds for 0.5 L/16 oz.), Light, effective, and even easier with it's innovative LCD screen. The Journey mates with the SteriPEN pre-filter and is sized between our Adventurer and Classic. Journey ships with two non-rechargeable (disposable) CR123 batteries. SteriPEN utilizes C Wavelength UV (ultraviolet light). UV-C light is short wave light, between x-rays and visible light wavelengths, which destroy the DNA of microbes in seconds. Without functional DNA, microbes can't reproduce or make you sick.