Defender destroys over 99.9% of bacteria, viruses and protozoa, including cryptosporidium and giardia…and does it quickly, a liter of water in just 90 seconds. And Defender is always ready, no pumping, no warming up, no filters, no testing, no waiting.

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SteriPEN Defender. Your state-of-the-art safe hydration solution. No other water treatment system matches its combination of effectiveness, speed, light weight and ease of use.

Made in the USA for military use, Defender destroys over 99.9% of bacteria, viruses and protozoa, including cryptosporidium and giardia. The germicidal UV light disinfects 1  liter of water in just 90 seconds.

SteriPEN Defender is always ready, no pumping, no warming up, no filters, no testing, no waiting.

SteriPEN Defender’s durability performs in the most hostile of environments, powered by 4 AA lithium batteries (included), with each set providing up to 200 one-half liters of water. The device adds just 5.5 oz. (156 g) to your pack.

During Military operations, SteriPEN water purifiers provide the advantage of collecting water an purifying later in a safe zone.

Additional Information
Weight 5.5 oz
Dimensions 7.6 x 1.5 x 1.5 in
MSRP $149.95
Lamp Life 8,000 treatments
Battery AA Lithium (Not included with purchase)
Battery Life Lithium Disposable: 200 treatments (16oz./0.5L), NiMH: 200 treatments (16oz./0.5L); Alkaline & NiCd not recommended.
Minimium Bottle Diameter 20mm (0.8 inches)
Filter Compatability Tapered End (PreFilter and FitsAll)
User Guide en
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We have cycled thousands of kilometers, from the United States to El Salvador and we have used our SteriPEN Adventurer Opti every day while riding to purify our drinking water.
Nico El Salvador
Andrea Rees
Loving my Freedom @SteriPEN, what a difference and that's just in Paris & Nice so far! Love that I can get clean water anytime, anywhere.
Andrea Rees Paris, France
Lea Conlon
During our 5 week Hugging the Coast Kayak Expedition (research on seaweed) in northern Sulawesi, Indonesia we use used our SteriPENs every day! 
Lea Conlon Indonesia

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FAQs for Defender

Q: Why is Defender more expensive than similar models?
— Asked on January 17, 2014
A: Defender is assembled in the United States to meet US Government Military Purchase Guidelines for large volume purchases resulting in a higher cost. If you are looking to purchase SteriPEN in small quantities for consumer use, we highly recommend you purchase the consumer model such as Classic, Traveler, or Emergency.
Q: My Journey malfunctions intermittently with a flashing unhappy face circle and unhappy face battery display. Sometimes it works OK and sometimes it gets set up with the 1L indicator but as soon as I put it in the water the unhappy faces come up. What's the story here? Thanks, Nat
— Asked by nat crosman on April 12, 2014
A: Hi Nat, The reason for the unhappy face when you place the Journey in water is dependent on where you are seeing it. If you don't have the User Guide that came with your SteriPeN, you can find it here: Please feel free to contact our customer support department at [email protected]
Q: I've loved my SteriPEN Adventure Opti for about 2 years, but have only used it about 30-40 times. When I started use this year, it responds as normal with a green light, then flashing green as well as flashing LED next to the UV light. The UV light doesn't seem to be lighting though. How can I verify it's working? What manufacturer warranties are on my pen?
— Asked by Micah Christiansen on April 14, 2014
A: Hi Micah - The indicators you describe sound like your Adventurer Opti is functioning normally. If you need no longer have your User Guide and need help remember the how the indicator lights work, you can find a copy of the instructions here: For safety reasons, the UV light will not turn on until it is placed in water. If you are unsure that it is lighting in water, we recommend placing it in a clear glass, possibly dimming the lights so that the light from the lamp is easily observed. If then you believe it isn't on, please contact our customer support department at 888-826-6234. Your SteriPEN comes with a 3-year warrantee and we are here to help!

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